Little monkeys and little apes scratching skin on crotch (4)
I believe the answer is:
imps
'little monkeys' is the definition.
(both can mean misbehaving children)
'little apes scratching skin on crotch' is the wordplay.
'little apes scratching' becomes 'im' (I can't justify this - if you can you should give a lot more credence to this answer).
'skin on' says to hollow out the word (remove centre letters) (outside letters).
'crotch' becomes 'puss' (puss is a kind of crotch).
'puss' with its middle removed is 'ps'.
'im'+'ps'='IMPS'
'and' is the link.
(Other definitions for imps that I've seen before include "repairs (for a wing)" , "Little mischievous devils" , "Children causing trouble" , "Little monkeys?" , "Small devils or mischievous children" .)