Travel always upset canvasser (4)
I believe the answer is:
goya
'canvasser' is the definition.
Both the answer and definition are singular nouns.
Maybe there's an association between them I don't understand?
'travel always upset' is the wordplay.
'travel' becomes 'go' ('go' can be a synonym of 'travel').
'always' becomes 'ay'.
'upset' is a reversal indicator.
'ay' back-to-front is 'ya'.
'go'+'ya'='GOYA'
Can you help me to learn more?
(Other definitions for goya that I've seen before include "Francisco de ---- (1746-1828), Spanish painter of portraits" , "Spanish painter, d. 1828" , "Spanish painter (Los Caprichos)" , "Ay, go to see great Spanish painter" , "Portrait painter" .)