Play tune by artist originally labelled 'unremarkable' (7)
I believe the answer is:
neutral
'unremarkable' is the definition.
(both can mean bland or ordinary)
'play tune by artist originally labelled' is the wordplay.
'play' indicates anagramming the letters.
'by' says to put letters next to each other.
'artist' becomes 'ra' (Royal Academician, member of Royal Academy of Arts).
'originally' suggests taking the first letters.
The first letter of 'labelled' is 'l'.
'tune' with letters rearranged gives 'neut'.
'neut'+'ra'+'l'='NEUTRAL'
(Other definitions for neutral that I've seen before include "nondescript colour" , "uncommitted to either side" , "Impartial; beige" , "Inoffensive; beige colour" , "On the fence" .)