On which no rag can be played? (5)
I believe the answer is:
organ
'on which no rag can be played?' is the definition.
I can't tell whether this defines the answer.
'on which no rag can be' is the wordplay.
'on which' becomes 'o' (I can't explain this - if you can you should give a lot more credence to this answer).
'no' becomes 'n' (common abbreviation y/n).
'can be' indicates an anagram.
'n'+'rag'='nrag'
'nrag' is an anagram of 'rgan'.
'o'+'rgan'='ORGAN'
Can you help me to learn more?
(Other definitions for organ that I've seen before include "Ear, perhaps" , "notes issue from this" , "Brain, for example - instrument" , "music producer" , "specialist magazine" .)