Remove light from chest in study (6)
I believe the answer is:
darken
'remove light from' is the definition.
(I've seen this in another clue)
'chest in study' is the wordplay.
'chest' becomes 'ark' (historical term for a chest).
'in' means one lot of letters goes inside another.
'study' becomes 'den' (den can mean an office or study).
'ark' inserted inside 'den' is 'DARKEN'.
(Other definitions for darken that I've seen before include "Cloud over" , "Grow blacker" , "Make less light" , "Grow less light" , "shade" .)