Rejection of French love gripping man's heart (6)
I believe the answer is:
denial
'rejection' is the definition.
(I've seen this before)
'of french love gripping man's heart' is the wordplay.
'of french' becomes 'de'.
'love' becomes 'nil' (I've seen this before).
'gripping' means one lot of letters goes inside another.
'heart' indicates the central letters.
The centre of 'man' is 'a'.
'nil' enclosing 'a' is 'nial'.
'de'+'nial'='DENIAL'
(Other definitions for denial that I've seen before include "Refusal to accept an unpalatable truth" , "Rejection or refusal" , "Negation" , "Saying it isn't so" , "Act of asserting that something alleged is not true" .)