Threatened strike that doesn't come off (5)
I believe the answer is:
feint
'strike that doesn't come off' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Maybe you can see an association between them that I don't see?
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for feint that I've seen before include "Mock attack" , "Pretended blow" , "False fencing trust sounds dim" , "Deceptive motion" , "(Make a) deceptive move" .)