Ghost, one consumed by anger (6)
I believe the answer is:
wraith
'ghost' is the definition.
(I've seen this before)
'one consumed by anger' is the wordplay.
'one' becomes 'i' (Roman numeral).
'consumed by' is an insertion indicator.
'anger' becomes 'wrath' (wrath is a kind of anger).
'i' placed within 'wrath' is 'WRAITH'.
(Other definitions for wraith that I've seen before include "Ghostly figure" , "Spook" , "looking pale and thin" , "Presence" , "Wrath I directed at spirit" .)