Insolence returned by dour traveller (7)
I believe the answer is:
pilgrim
'traveller' is the definition.
(pilgrim is a kind of traveller)
'insolence returned by dour' is the wordplay.
'insolence' becomes 'lip' (I've seen this before).
'returned' says the letters should be written backwards.
'by' says to put letters next to each other.
'dour' becomes 'grim' (synonyms).
'lip' backwards is 'pil'.
'pil'+'grim'='PILGRIM'
(Other definitions for pilgrim that I've seen before include "One journeying to shrine etc" , "Traveller to shrine etc" , "Christian, say" , "One journeying to holy place" , "... emigrants to Massachusetts" .)