Dark side of Sir Lancelot we hear (5)

I believe the answer is:

night

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

I don't understand the remainder of the clue.

(Other definitions for night that I've seen before include "''Tender is the ...'' (F Scott Fitzgerald)|" , "Time without 10" , "Hours of darkness" , "death" , "Dark period" .)

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

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