Person who fancies another (7)
I believe the answer is:
admirer
'person who fancies another' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for admirer that I've seen before include "Romantic adorer" , "sweetheart" , "Married to suitor" , "Married (anag) -- lover" , "One who regards (someone) with respect" .)