Lover tied knot, did you say? (4)
I believe the answer is:
beau
'lover' is the definition.
(beau is a kind of lover)
'tied knot did you say?' is the wordplay.
'tied knot' becomes 'bow'.
'did you say?' indicates a 'sounds like' (homophone) clue.
'bow' is a homophone of 'BEAU'.
(Other definitions for beau that I've seen before include "Sweetheart" , "Handsome man" , "Dapper fellow" , "One loving" , "An old-fashioned boy friend (4)" .)