Nearly time when The Sun sinks into obscurity (5)

I believe the answer is:

night

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'obscurity' is the definition.
(thesaurus)

'nearly time' is the wordplay.
'nearly' becomes 'nigh' ('nigh' can be a synonym of 'nearly'**).
'time' becomes 't'.
'nigh'+'t'='NIGHT'

'when the sun sinks into' acts as a link.
This may not be correct. Some or all of it may belong to another bit of the clue.

Can you help me to learn more?

(Other definitions for night that I've seen before include "Thing (anag)" , "Darkness; see you in the morning" , "Time for turning" , "Time of darkness" , "That's when it's darkest" .)

I've seen this clue in The Telegraph.

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