In trouble receiving fine, not popular penalty (7)
I believe the answer is:
forfeit
'penalty' is the definition.
(I know that forfeit is a type of penalty)
'in trouble receiving fine not popular' is the wordplay.
'in' means one lot of letters goes inside another.
'trouble receiving' becomes 'forit' (I can't justify this - if you can you should believe this answer much more).
'not' indicates named letters should be taken away.
'popular' becomes 'in' ('in' can mean trendy).
'fine' with 'in' removed is 'fe'.
'forit' going around 'fe' is 'FORFEIT'.
Can you help me to learn more?
(Other definitions for forfeit that I've seen before include "Effort I made to pay penalty" , "Penalty for wrongdoing" , "Fine, penalty; give up" , "Give up or lose the right to something" , "It has to be paid or given up as a penalty" .)