Hot bap topping, perhaps (2,1,4)
I believe the answer is:
on a roll
'hot' is the definition.
(I've seen this in another clue)
'bap topping perhaps' is the wordplay.
I cannot quite understand how this works, but
'bap' could be 'roll' (I've seen this before) and 'roll' is located in the answer.
The remaining letters 'ona' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for on a roll that I've seen before include "Having long spell of good luck" , "Piano music was once stored here" , "Where one may find sesame seeds" , "Where registered names are" , "enjoying continuing success" .)