Lots again suffering homesickness (9)
I believe the answer is:
nostalgia
'homesickness' is the definition.
(thesaurus)
'lots again suffering' is the wordplay.
'suffering' is an anagram indicator.
'lots'+'again'='lotsagain'
'lotsagain' with letters rearranged gives 'NOSTALGIA'.
(Other definitions for nostalgia that I've seen before include "Remembrance of Things Past" , "Sentimental feeling of analogist" , "fondly looking back" , "Wistfulness" , "Longing for things past" .)