Faulty info about love causes resentment (7)
I believe the answer is:
dudgeon
'resentment' is the definition.
(I've seen this before)
'faulty info about love' is the wordplay.
'faulty' becomes 'dud' (I've seen this before).
'info' becomes 'gen' (informal term for information).
'about' indicates putting letters inside.
'love' becomes 'o' (love means zero in tennis).
'gen' going around 'o' is 'geon'.
'dud'+'geon'='DUDGEON'
'causes' is the link.
(Other definitions for dudgeon that I've seen before include "Offended indignation" , "Deep resentment" , "Devil's Disciple" , "(High) resentment" , "indignant state" .)