Argument about son in love (7)
I believe the answer is:
worship
'love' is the definition.
(worship is a kind of love)
'argument about son in' is the wordplay.
'argument' becomes 'row' (I've seen this before).
'about' shows that the letters should be reversed in order.
'son' becomes 's'.
'in' becomes 'hip' (both can mean fashionable**).
'row' backwards is 'wor'.
'wor'+'s'+'hip'='WORSHIP'
(Other definitions for worship that I've seen before include "Adoration of a divine being" , "Devotions" , "Veneration" , "Be very keen on" , "Love" .)