Confront fellow expert (4)
I believe the answer is:
face
'confront' is the definition.
(I know that confront is a kind of face)
'fellow expert' is the wordplay.
'fellow' becomes 'f' (abbreviation - of a society etc.).
'expert' becomes 'ace' (ace can informally mean very good).
'f'+'ace'='FACE'
(Other definitions for face that I've seen before include "Outward appearance" , "Deal with" , "Confront - mug (slang)" , "Countenance, visage" , "Cope with" .)