Smooch: a little peck is similar (4)
I believe the answer is:
kiss
'smooch' is the definition.
(I know that smooch can be written as Kiss)
'a little peck is similar' is the wordplay.
'a little' indicates the answer is hidden within the clue (a little bit of the clue).
'KISS' is hidden in the letters of 'peck is similar'.
(Other definitions for kiss that I've seen before include "x (that may be French)" , "Peck (on cheek or lips?)" , "Embrace" , "Buss" , "Neck - peck" .)