Musician in small room is close to vocalist (7)
I believe the answer is:
cellist
'musician' is the definition.
(cellist is a kind of musician)
'small room is close to vocalist' is the wordplay.
'small room' becomes 'cell' (I've seen this before).
'close to' indicates one should take the final letters (the close/ending of).
The final letter of 'vocalist' is 't'.
'cell'+'is'+'t'='CELLIST'
'in' acts as a link.
(Other definitions for cellist that I've seen before include "E.g. Casals, du Pre" , "Du Pre or Lloyd Weber" , "Lloyd Webber?" , "Musician in string section" , "String player" .)