Search for crest (4)
I believe the answer is:
Here is my best explanation:
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 "Carefully search", "groom?", "Toothed device - crest", "Device for tidying one's appearance", "For use on hair", "Red crest on a cock's head", "Toothed instrument", "Cock's crest", "Honey structure" and "Systematically search".)