Look for an expert on France (4)
I believe the answer is:
face
'look for' is the definition.
(thesaurus)
'an expert on france' is the wordplay.
'an expert' becomes 'ace' (ace is a kind of expert).
'on' is a charade indicator (letters next to each other).
'france' becomes 'f'.
'ace' put after 'f' is 'FACE'.
(Other definitions for face that I've seen before include "Cope with" , "Front -- confront" , "celebrity" , "Countenance, visage" , "steep side of mountain" .)