Challenger (5)
There are a few possibilities for this:
contender
'challenger' is the definition.
(I know that challenger can be written as rival)
This is all the clue.
(Other definitions for rival that I've seen before include "Be equal to in quality" , "Adversary or foe" , "Close competitor" , "Someone you hope to defeat" , "Competing opponent" .)
'challenger' is the definition.
(I've seen this in another clue)
This is all the clue.
'challenger' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for contender that I've seen before include "One engaged in a struggle" , "One striving" , "one in the field" , "Candidate" , "One seeking title" .)