Vampire saga with one large drunk outside (8)

I believe the answer is:

twilight

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'vampire saga' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.

'with one large drunk outside' is the wordplay.
'with' becomes 'w' (abbreviation).
'one' becomes 'i' (Roman numeral).
'large' becomes 'L' (eg in clothes sizes).
'drunk' becomes 'tight' (slang term).
'outside' indicates putting letters inside.
'w'+'i'+'l'='wil'
'wil' put within 'tight' is 'TWILIGHT'.

Can you help me to learn more?

(Other definitions for twilight that I've seen before include "Evening glow" , "Period of gradual decline or obscurity" , "Glow after sunset" , "Condition of decline" , "Time of day following sunset" .)

I've seen this clue in The Independent and The Sun.

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