Generous amount of heavy sarcasm? (1,3,3)
I believe the answer is:
a fat lot
'sarcasm?' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.
'generous amount of heavy' is the wordplay.
I cannot really understand how this works, but
'amount' could be 'lot' (lot is a kind of amount) and 'lot' is found within the answer.
'heavy' could be 'fat' (similar in meaning) and 'fat' is found within the answer.
A single letter 'a' remains which might be clued in a way I don't see.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Another definition for a fat lot that I've seen is " Not much".)