If somebody is a C cup but they have no cleavage, is there any way to achieve that?

Great question!  Depending on what your breasts look like and how close of a cleavage you desire it could be possible.  Placing implants will provide you with a closer and improved cleavage contour.  If you need a lift as well, it can help.  It really all depends on the exact procedure that needs to be done to achieve the goals you desires.  Therefore it is important to have a consultation with a board certified plastic surgeon so that appropriate procedure can be explained to you in detail.Best of luck and hope this information helps!
- Dr. Roger Tsai  @DrRogerTsai
Board Certified Plastic Surgeon

You did not post photos. If your breasts are wide apart, they will always be wide apart. We cannot move the bases of the breasts. However, fat transfers and wider implants can help fill in gaps.

Thank you for the question.
 Some general thoughts may be helpful to you. Much of the final look and feel achieved after breast augmentation surgery depends on several factors:
1. The initial shape, size (volume of breast tissue), symmetry of the patient's breasts. In general, the better the preoperative breast appearance the more likely the breast augmentation “look” will be optimal. 
Generally speaking, the patient's specific anatomy ( for example, relatively wide space between the breasts) may limit how close the medial breast folds ( cleavage) will be after breast   augmentation surgery.   Also,  a patient's nipple/areola complex position must also be taken into account; keep in mind that the breast implants must be centered  appropriately under each nipple/areola complex. Otherwise, the nipple/areola complexes will seem off-center on each breast mound.
2. The experience/skill level of the surgeon is important in determining the final outcome. For example, the accurate and gentle dissection of the breast implant pockets are critical in producing long-term well-placed breast implants. I personally think that these 2 factors are more important than any others, including type (saline or silicone) or model (low/moderate/high profile) of implant.
3. The type of implant used may determine the final outcome, especially if the patient does not have significant covering breast or adipose tissue. For example, some surgeons feel that silicone implants have a more natural look and feel than saline implants because silicone gel has a texture that is similar to breast tissue. In other words, if a patient has very low body fat and/or very little breast tissue, the silicone gel implants may provide a more "natural" result.  I find that I use round smooth silicone gel breast implants for the vast majority of patients who seek breast augmentation surgery.
4. The size and model of breast implant used may make a significant difference in the final outcome. Therefore, it is very important to communicate your size goals with your surgeon. In my practice, the use of photographs of “goal” pictures (and breasts that are too big or too small) is very helpful. I have found that the use of words such as “natural” or “D or DD cup” etc may mean different things to different people. 
Also, as you know, cup size varies depending on who makes the bra; therefore, discussing desired cup size may also be inaccurate.
  To summarize: select your plastic surgeon carefully. Communicate your goals carefully as well.  Chances are you will be very pleased with the outcome of breast augmentation surgery. 
I hope this helps. Best wishes.