Cat left snake trapped? It's fair game (7)
I believe the answer is:
tombola
'it's fair game' is the definition.
(I've seen this before)
'cat left snake' is the wordplay.
'cat' becomes 'tom' (a tom is a male cat).
'left snake' becomes 'bola' (I can't justify this - if you can you should give a lot more credence to this answer).
'tom'+'bola'='TOMBOLA'
'trapped?' is the link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for tombola that I've seen before include "Type of lottery" , "gambling activity" , "Rotating drum game" , "Fair game" , "Lamb too (anag) - game with prizes" .)