Average is capital! (5)
I believe the answer is:
paris
'capital' is the definition.
(Paris is an example)
'average is' is the wordplay.
'average' becomes 'par' (I've seen this before).
'par'+'is'='PARIS'
(Other definitions for paris that I've seen before include "City; Juliet's betrothed Count" , "Eiffel Tower city" , "I spar (anag)" , "Trojan prince who abducted Helen" , "'''I love ... in the springtime'' (Cole Porter) (5)'" .)