Unexpected contender (4,5)
I believe the answer is:
dark horse
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">unexpected contender</span>' is the definition.<br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for dark horse that I've seen before include "it may be foolish to discount" , "Unknown quantity" , "Little-known competitor like shadowy equine" , "Unfancied winner" , "Candidate, not well known" .)