Not exactly a contest (5)
I believe the answer is:
about
'not exactly' is the definition.
(I've seen this before)
'a contest' is the wordplay.
'contest' becomes 'bout' (I've seen this in other clues).
'a'+'bout'='ABOUT'
(Other definitions for about that I've seen before include "On the subject of, approximately" , "In the area of or in relation to" , "Close to" , "Engaged in" , "In conection with, all around" .)