Card for the expert (3)
I believe the answer is:
ace
I believe this clue is a double definition.
'card' is the first definition.
(ace is a type of playing card)
'the expert' is the second definition.
(ace can informally mean very good)
'for' acts as a link.
(Other definitions for ace that I've seen before include "One or 11 in cards" , "Outstanding" , "Test pilot'" , "Hole in one; card" , "Hole in one; very good" .)