Red Reg slurps contains sediment (5)

I believe the answer is:

dregs

'sediment' is the definition.
(dregs is a kind of sediment)

'red reg slurps contains' is the wordplay.
'contains' says the answer is hidden in the clue.
'DREGS' is hidden within 'red reg slurps'.

(Other definitions for dregs that I've seen before include "Sediment at bottom of drink" , "Remnant of drink" , "Sediment, grounds" , "Liquid remnants with sediment" , "Fluid remnants" .)

I've seen this clue in The Guardian.

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