Something used in a supporting role? (4)
I believe the answer is:
prop
'supporting role?' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'something used in a' is the wordplay.
'something' becomes 'pro' (I can't justify this - if you can you should believe this answer much more).
'used in' means to look at the middle letters (the letters used on the inside of the word).
'a' becomes 'alpha' (the Greek letter A).
The central letter of 'alpha' is 'p'.
'pro'+'p'='PROP'
Can you help me to learn more?
(Other definitions for prop that I've seen before include "Driving mechanism" , "Lean" , "Moveable object used on stage" , "Stay" , "Support; object used on stage" .)