Johann Sebastian abandoned hardback after the sun went down (4)
I believe the answer is:
dark
'johann sebastian' is the definition.
The definition suggests a singular noun which matches the answer.
'abandoned hardback after the sun went down' is the wordplay.
I cannot really understand how this works, but
'down' could be 'd' and 'd' is located in the answer.
The remaining letters 'ark' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for dark that I've seen before include "Black, perhaps - night" , "Devoid of brightness" , "Closed as theatre" , "Overcast" , "With little or no light" .)