Case worker is someone who likes to abstain from drink (6)

I believe the answer is:

porter

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'drink' is the definition.
(porter is a kind of drink)

I don't understand the remainder of the clue.

(Other definitions for porter that I've seen before include "Baggage-handler" , "Cole - - , songwriter" , "Cole - - , composer" , "Bag carrier in hotel or railway station" , "Doorkeeper; dark beer" .)

I've seen this clue in The Telegraph.

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