Admirer who gets nothing right (5)
I believe the answer is:
lover
'admirer' is the definition.
(I've seen this before)
'nothing right' is the wordplay.
'nothing' becomes 'love' (love is zero in tennis).
'right' becomes 'r' (common abbreviation).
'love'+'r'='LOVER'
'who gets' is the link.
(Other definitions for lover that I've seen before include "Romeo (or Juliet)" , "Romantic partner" , "admirer" , "Suitor" , "One has favourite" .)