Traveller turned fighter, nursing right cheek (7)
I believe the answer is:
pilgrim
'traveller' is the definition.
(I know that pilgrim is a type of journeyer)
'turned fighter nursing right cheek' is the wordplay.
'turned' is a reversal indicator.
'fighter' becomes 'mig' (fighter jet produced by Russian company MiG).
'nursing' indicates putting letters inside.
'right' becomes 'r' (common abbreviation).
'cheek' becomes 'lip' (both can mean insolence or rudeness).
'mig' placed around 'r' is 'mirg'.
'mirg'+'lip'='mirglip'
'mirglip' reversed gives 'PILGRIM'.
(Other definitions for pilgrim that I've seen before include "Traveller to a sacred place like Mecca" , "Traveller in sacred place for religious reasons" , "... emigrants to Massachusetts" , "One on journey to shrine" , "Traveller to a holy place" .)