A Parisian holds a contest in the dark (7)
I believe the answer is:
unaware
'in the dark' is the definition.
(I've seen this before)
'a parisian holds a contest' is the wordplay.
'a parisian' becomes 'une' ('a' in French).
'holds' indicates putting letters inside.
'contest' becomes 'war' (military contest).
'a'+'war'='awar'
'une' placed around 'awar' is 'UNAWARE'.
(Other definitions for unaware that I've seen before include "In the dark" , "Unknowing" , "Not knowing (of a situation or fact)" , "Without knowledge" , "Ignorant - unacquainted" .)