Unlit, deserted animal sanctuary (4)
I believe the answer is:
dark
'unlit' is the definition.
(similar in meaning)
'deserted animal sanctuary' is the wordplay.
'deserted' becomes 'd'.
'animal sanctuary' becomes 'ark' (as in Noah's Ark).
'd'+'ark'='DARK'
(Other definitions for dark that I've seen before include "Nearer black than white" , "Saturnine" , "Devoid of brightness" , "Sinister - evening" , "Devoid of light" .)