Sentimental fondness (4,4)
I believe the answer is:
soft spot
'sentimental fondness' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for soft spot that I've seen before include "showing fondness" , "Sentimental affection" , "Affectionate weakness for (someone/something)" , "Sentimental fondness" , "Emotional susceptibility" .)