Needs to remove top for insects (4)
I believe the answer is:
ants
'insects' is the definition.
(ant is a kind of insect)
'needs to remove top' is the wordplay.
'needs' becomes 'wants' ('want' can be a synonym of 'need').
'to remove top' means to remove the first letter (I've seen 'removes top' mean this).
'wants' with its first letter taken off is 'ANTS'.
'for' is the link.
(Other definitions for ants that I've seen before include "Hard workers" , "24 [INSECT] s" , "They live in a formicary" , "Small social insects" , "Six-foot insects" .)