Unaccompanied artist holds on (6)
I believe the answer is:
lonely
'unaccompanied' is the definition.
(thesaurus)
'artist holds on' is the wordplay.
'artist' becomes 'lely' (I've seen this before).
'holds' indicates putting letters inside.
'lely' enclosing 'on' is 'LONELY'.
(Other definitions for lonely that I've seen before include "In want of company" , "Feeling a lack of companionship" , "Without companionship" , "Forlorn, solitary" , "Short of companionship" .)