Arch-sounding lover (4)
I believe the answer is:
beau
'lover' is the definition.
(beau is a kind of lover)
'arch-sounding' is the wordplay.
'arch' becomes 'bow' (I've seen this before).
'sounding' indicates a 'sounds like' (homophone) clue.
'bow' sounds like 'BEAU'.
(Other definitions for beau that I've seen before include "Sweetheart" , "Male admirer; dandy" , "Lover boy" , "An old boy friend like Brummel?" , "Handsome young lover" .)