Room only for music maker (5)
I believe the answer is:
cello
'music maker' is the definition.
(cello is a kind of musical instrument)
'room only' is the wordplay.
'room' becomes 'cell' (cell is a kind of room).
'only' becomes 'o' (this might be a standard abbreviation which I don't know about).
'cell'+'o'='CELLO'
'for' acts as a link.
Can you help me to learn more?
(Other definitions for cello that I've seen before include "Tortelier's instrument" , "Viola's bigger brother?" , "has strings attached" , "large-scale fiddle" , "big fiddle?" .)