Ghosts, or spectres (7)
I believe the answer is:
wraiths
I believe this is a double definition.
'ghosts' is the first definition.
(I know this)
'spectres' is the second definition.
('wraith' can be a synonym of 'spectre')
(Other definitions for wraiths that I've seen before include "spirits are made" , "They haunt" , "Spectres" .)