Skilled worker in paintings is a knight (7)
I believe the answer is:
artisan
'skilled worker' is the definition.
(an artisan is a skilled craftsperson)
'paintings is a knight' is the wordplay.
'paintings' becomes 'art' (painting is a type of artwork).
'knight' becomes 'N' (chess abbreviation).
'art'+'is'+'a'+'n'='ARTISAN'
'in' acts as a link.
(Other definitions for artisan that I've seen before include "Skilled worker at craft or trade" , "Handy worker" , "man with skill" , "Crafty sort" , "Skilled tradesman" .)