Longing, looking back again, lots fancy (9)
I believe the answer is:
nostalgia
'longing looking back' is the definition.
'nostalgia' can be an answer for 'longing' (thesaurus). I am unsure of the 'looking back' bit.
'again lots fancy' is the wordplay.
'fancy' indicates anagramming the letters.
'again'+'lots'='againlots'
'againlots' with letters rearranged gives 'NOSTALGIA'.
Can you help me to learn more?
(Other definitions for nostalgia that I've seen before include "A longing for past times" , "Longing for what's gone" , "That may bring on homesickness" , "Sentimental longing for the past" , "Attraction to the past" .)