Former lover refers to tickles (7)
I believe the answer is:
excites
'tickles' is the definition.
(both can mean to thrill or amuse)
'former lover refers to' is the wordplay.
'former lover' becomes 'ex'.
'refers to' becomes 'cites' ('cite' can be a synonym of 'refer to').
'ex'+'cites'='EXCITES'
(Other definitions for excites that I've seen before include "Stirs up, rouses" , "Provokes" , "Makes eager" , "Arouses feelings in" , "Animates" .)