Love gear, popular creation (6)
I believe the answer is:
origin
'creation' is the definition.
(thesaurus)
'love gear popular' is the wordplay.
'love' becomes 'o' (love means zero in tennis).
'gear' becomes 'rig' (rig is a kind of gear).
'popular' becomes 'in' ('in' can mean trendy).
'o'+'rig'+'in'='ORIGIN'
(Other definitions for origin that I've seen before include "Point of creation" , "For a start" , "Crossing of axes" , "Beginning, starting point" , "Where axes cut" .)