Unsuccessful person is nearer, but not first (5)
I believe the answer is:
loser
'unsuccessful person' is the definition.
(synonyms)
'nearer but not first' is the wordplay.
'nearer' becomes 'closer' ('close' can be similar in meaning to 'near').
'but not first' means to remove the first letter.
'closer' with its initial letter removed is 'LOSER'.
'is' is the link.
(Other definitions for loser that I've seen before include "Winner's opponent" , "Generally inept" , "sad type?" , "One not winning" , "A failure, also-ran" .)