Sentimental longing (9)
I believe the answer is:
nostalgia
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">sentimental longing</span>' is the definition.<br/ >'<span class="explanation-format__answer">nostalgia</span>' can be an answer for '<span class="explanation-format__original">longing</span>' <span class="explanation-format__explanation">(nostalgia is a kind of longing)</span>. I also know that 'sentimental' relates to this answer.<br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for nostalgia that I've seen before include "longing for home and family" , "Fond memories" , "Sense of past perfect" , "That may bring on homesickness" , "Longing for what's gone" .)