In stage productions, used for casting (3)
I believe the answer is:
rod
'for casting' is the definition.
The answer and definition can be both man-made objects as well as being singular nouns.
Maybe you can see a link between them that I can't see?
'in stage productions' is the wordplay.
'in' says the answer is hidden in the clue.
'ROD' is hidden within 'stage productions'.
'used' is the link.
Can you help me to learn more?
(Other definitions for rod that I've seen before include "Fishing implement" , "Straight, slender stick" , "Instrument of punishment" , "Little boy" , "Imperial measure" .)