Ghosts in sunglasses (6)
I believe the answer is:
shades
I believe this is a double definition.
'ghosts' is the first definition.
('shade' can be a synonym of 'ghost')
'sunglasses' is the second definition.
(synonyms)
'in' acts as a link.
(Other definitions for shades that I've seen before include "suspicions" , "Poetic ghosts or American sunglasses" , "Sunglasses, colloquially" , "Cool sunglasses or archaic ghosts" , "'Tints, tones (6)'" .)