Search for appearance (4)
I believe the answer is:
look
This clue is a double definition.
'search for' is the first definition.
(thesaurus)
'appearance' is the second definition.
(look is a kind of appearance)
(Other definitions for look that I've seen before include "Watch, observe" , "Facial expression" , "Appear - search" , "Seem" , "Get an eyeful" .)