Wailing wraith: she's in torment (7)
I believe the answer is:
banshee
'wailing wraith' is the definition.
(I've seen this in another clue)
'she's in torment' is the wordplay.
'in' means one lot of letters goes inside another.
'torment' becomes 'bane' (as in the bane of someone's life).
'she' going within 'bane' is 'BANSHEE'.
(Other definitions for banshee that I've seen before include "Howler" , "Irish female spirit who warns of an impending death" , "Wailing spirit of Irish folklore" , "Sign of imminent death" , "Wailing woman warning of a death" .)