Search for an appearance (4)
I believe the answer is:
look
This clue is a double definition.
'search for' is the first definition.
(thesaurus)
'an appearance' is the second definition.
(I know that look is a type of countenance)
(Other definitions for look that I've seen before include "Facial expression" , "Mien" , "Seem" , "Inspect" , "See; appearance" .)