Decisive, often after credit (6)
I believe the answer is:
crunch
'credit' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe they are linked in a way I don't understand?
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for crunch that I've seen before include "Crush with the teeth" , "Informally, a decisive event or showdown" , "Decisive moment" , "Chew something hard" , "moment of difficulty" .)