By Robin, is it modern music? (5)
I believe the answer is:
adair
'by robin' is the definition.
'adair' can be an answer for 'robin' (I've seen this in another clue). I'm not sure about the 'by' bit.
'it modern music?' is the wordplay.
I cannot really understand how this works, but
'modern' could be 'ad' (I've seen this in other clues) and 'ad' is located in the answer.
'music?' could be 'air' (air is a kind of music) and 'air' is found within the answer.
No letters remain.
This explanation may well be incorrect...
'is' acts as a link.
Can you help me to learn more?
(Another definition for adair that I've seen is " Robin - - (old song)".)