Homesickness (9)
I believe the answer is:
nostalgia
'homesickness' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for nostalgia that I've seen before include "A longing for past times" , "Fond memories" , "dreaming of the past" , "Longing for something past - isn't a goal (anag)" , "Sentimental feeling of analogist" .)