Sentimental weakness (4,4)
I believe the answer is:
soft spot
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sentimental weakness</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for soft spot that I've seen before include "Sentimental fondness" , "Emotional susceptibility" , "Sentimental affection" , "showing fondness" , "Affectionate weakness for (someone/something)" .)