Ghosts begin to shudder, encountering hell (6)
I believe the answer is:
shades
'ghosts' is the definition.
(I know this)
'shudder encountering hell' is the wordplay.
'shudder' becomes 's' (this might be a standard abbreviation of which I'm unaware).
'encountering' means one lot of letters go next to another.
'hell' becomes 'hades' (synonyms).
's'+'hades'='SHADES'
'begin to' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
(Other definitions for shades that I've seen before include "Poetic ghosts or American sunglasses" , "disguise, sometimes" , "Sunglasses, colloquially" , "Hip sunglasses or gloomy ghosts" , "glasses?" .)