Lost again, wandering in state of wistfulness (9)
I believe the answer is:
nostalgia
'state of wistfulness' is the definition.
'nostalgia' can be an answer for 'wistfulness' (I've seen this before). I am not certain of the 'state of' bit.
'lost again wandering' is the wordplay.
'wandering' indicates an anagram.
'lost'+'again'='lostagain'
'lostagain' is an anagram of 'NOSTALGIA'.
'in' is the link.
Can you help me to learn more?
(Other definitions for nostalgia that I've seen before include "Longing for things past" , "Remembrance of Things Past" , "Sense of past perfect" , "That may bring on homesickness" , "Yearning for past - homesickness" .)