Cow lick is when hair shaft directions don't follow the natural pattern that is expected in the areas. It may make the hair look thinner in crown or hairline and it can also affect the styling of hair for individuals. It could be corrected with hair restoration since the doctors have full control on the direction and position of each hair follicle that is implanted.
If posteriorly growing hair affects up to half your stable hairline, it would be very difficult to surgically correct it. If the unfavorably growing hairs are limited to a centimeter, excision might work followed at a later date with forward growing hair transplants.
I am not sure which type of 'lick' you are talking about. There are frontal and crown licks. The classic Cow lick is in the crown and these are almost impossible to change.The ones in the front; however, can be changed with hair transplantation.