Corners knights? (3,6)
I believe the answer is:
set pieces
'corners' is the definition.
(a corner is a type of set piece in football)
'knights?' is the wordplay.
I cannot really understand how this works, but
'knights?' could be 'pieces' (knight is a kind of piece) and 'pieces' is located in the answer.
The remaining letters 'set' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for set pieces that I've seen before include "Well-practised moves" , "Elaborate formal speeches" , "all 32 on board?" , "fireworks displays" , "men on chess board?" .)