Fine wicket at the start of a game (5)
I believe the answer is:
wispy
'fine' is the definition.
(I've seen this before)
'wicket at the start of a game' is the wordplay.
'at the start of' suggests taking the first letters (I've seen 'at the start' mean this).
'a game' becomes 'ispy' (I Spy is a guessing game).
The initial letter of 'wicket' is 'w'.
'w'+'ispy'='WISPY'
(Other definitions for wispy that I've seen before include "Flimsy" , "Lacking in distinction" , "Light and fine in texture" , "Straggly" , "Diaphanous" .)