Sinatra could be a skilled worker (7)
I believe the answer is:
artisan
'a skilled worker' is the definition.
(an artisan is a skilled craftsperson)
'sinatra could be' is the wordplay.
'could be' is an anagram indicator.
'sinatra' with letters rearranged gives 'ARTISAN'.
(Other definitions for artisan that I've seen before include "one in command of craft?" , "Egypt peninsula; holy Mount" , "Skilled manual 17" , "Technician" , "Smith" .)