You're unlikely to get fat on it (4,4)
I believe the answer is:
lean meat
'you're unlikely to' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'fat on it' is the wordplay.
I cannot quite understand how this works, but
'on' could be 'at' (I've seen this in other clues) and 'at' is located in the answer.
'it' could be 'e' ('e' can mean 'electronic' which is similar to 'IT') and 'e' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
'get' acts as a link.
Can you help me to learn more?
(Another definition for lean meat that I've seen is " Jack Sprat's preference".)