When fined, we hear, you just have to cough up (4)
I believe the answer is:
find
'cough up' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Maybe there's a link between them I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for find that I've seen before include "Locate or discover" , "Track down" , "Come across" , "Discover by chance" , "Acquisition" .)