Leave top game (9)
I believe the answer is:
partridge
'game' is the definition.
(game bird)
'leave top' is the wordplay.
'leave' becomes 'part' (parting means leaving or separating).
'top' becomes 'ridge' (I can't explain this - if you can you should believe this answer much more).
'part'+'ridge'='PARTRIDGE'
Can you help me to learn more?
(Other definitions for partridge that I've seen before include "early Christmas present" , "Animal" , "Game bird (in a pear tree?)" , "1st" , "Widespread bird" .)