Is such a competition a striking success? (8)
I believe the answer is:
knockout
'success?' is the definition.
(thesaurus)
'is such a competition a striking' is the wordplay.
I cannot really understand how this works, but
'striking' could be 'knock' (knock is a kind of striking) and 'knock' is found in the answer.
The remaining letters 'out' 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 knockout that I've seen before include "Boxing blow" , "The quietus in boxing" , "reverse of OK?" , "End of bout" , "Final stroke" .)