Search for crest (4)
I believe the answer is:
comb
This clue is a double definition.
'search' is the first definition.
(I've seen this before)
'crest' is the second definition.
(comb is a kind of crest)
'for' is the link.
(Other definitions for comb that I've seen before include "Red crest on a cock's head" , "Used to tidy hair" , "Toothed object for tidying hair" , "Toothed instrument" , "Implement with teeth" .)