Is a dark one a bad thing? (5)
I believe the answer is:
night
'is a dark one a' is the definition.
I can't tell whether this defines the answer.
'bad thing?' is the wordplay.
'bad' indicates an anagram.
'thing' is an anagram of 'NIGHT'.
Can you help me to learn more?
(Other definitions for night that I've seen before include "late" , "See 1 Across" , "period of gloom" , "Time for bed" , "The dark time" .)