Capital is average at first (5)
I believe the answer is:
paris
'capital' is the definition.
(capital of France)
'is average at first' is the wordplay.
'average' becomes 'par' (average score in golf).
'at first' says to put letters next to each other.
'is' put after 'par' is 'PARIS'.
(Other definitions for paris that I've seen before include "European capital city" , "European capital -- Trojan prince" , "An American in - -" , "European capital - Greek hero" , "Prince of Troy - capital city" .)