Room only for an instrument (5)

I believe the answer is:

cello

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'an instrument' is the definition.
(cello is a kind of instrument)

'room only' is the wordplay.
'room' becomes 'cell' (cell is a kind of room).
'only' becomes 'o' (this might be a standard abbreviation of which I'm unaware).
'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 "Musical instrument like large violin held between knees" , "large-scale fiddle" , "Musical instrument like large violin held between legs" , "has strings attached" , "Jacqueline du Pre's instrument" .)

I've seen this clue in The Mirror.

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