Competitor raced in European northern Tourist Trophy (7)
I believe the answer is:
entrant
'competitor' is the definition.
(someone who has entered a competition)
'raced in european northern tourist trophy' is the wordplay.
'raced' becomes 'ran' (running is a kind of racing).
'in' means one lot of letters goes inside another.
'european northern tourist trophy' becomes 'entt' (this could be a standard abbreviation which I don't know about).
'ran' put within 'entt' is 'ENTRANT'.
Can you help me to learn more?
(Other definitions for entrant that I've seen before include "Newcomer" , "One going in for exam" , "One competing" , "Contender" , "Who goes in" .)