Moves slowly in game that's not finished (6)
I believe the answer is:
inches
'moves slowly' is the definition.
(I've seen this before)
'in game that's not finished' is the wordplay.
'game' becomes 'chess' (chess is a kind of game).
'that's not finished' means to remove the last letter.
'chess' with its final letter taken away is 'ches'.
'in'+'ches'='INCHES'
(Other definitions for inches that I've seen before include "Niches (anag.)" , "Edges slowly" , "Twelves of these in a foot" , "Short lengths" , "Moves slowly and cautiously" .)