Still returning to ruined shelters, however (12)
I believe the answer is:
nevertheless
'however' is the definition.
('nevertheless' can be a synonym of 'however')
'still returning to ruined shelters' is the wordplay.
'still' becomes 'even' ('even' can be a synonym of 'still'**).
'returning' says the letters should be written backwards.
'to ruined' is an anagram indicator.
'even' reversed gives 'neve'.
'shelters' with letters rearranged gives 'rtheless'.
'neve'+'rtheless'='NEVERTHELESS'
(Other definitions for nevertheless that I've seen before include "However" , "Still" , "at any rate" , "In spite of everything" , "anyhow" .)