Josh reduced disc by variable European (6)
I believe the answer is:
wheeze
'josh' is the definition.
Both the answer and definition are singular nouns.
Perhaps you can see an association between them that I don't see?
'reduced disc by variable european' is the wordplay.
'reduced disc by' becomes 'whee' (I can't justify this - if you can you should believe this answer much more).
'variable' becomes 'z' (algebra).
'european' becomes 'e' (abbreviation e.g. EU).
'whee'+'z'+'e'='WHEEZE'
Can you help me to learn more?
(Other definitions for wheeze that I've seen before include "Sound of difficult breathing" , "Whistling breath and clever scheme" , "Sound in trouble when articulating" , "A crafty trick!" , "A good trick" .)