Dark disturbing thing (5)

I believe the answer is:

night

'dark' is the definition.
(it's dark at nighttime)

'disturbing thing' is the wordplay.
'disturbing' indicates anagramming the letters (I've seen this in other clues).
'thing' anagrammed gives 'NIGHT'.

(Other definitions for night that I've seen before include "Dark period" , "Time for turning" , "Darkness; see you in the morning" , "Time of darkness" , "Saturday -- Fever (film)" .)

I've seen this clue in The Globe and Mail.

Want a hint initially instead of a full solution? Install my app