One who may be seen mending a drain (5)

I believe the answer is:

sewer

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'a drain' is the definition.
(I know that sewer is a type of drain)

I don't understand the remainder of the clue.

(Other definitions for sewer that I've seen before include "Drainage conduit" , "Tailor" , "Large pipe for carrying waste matter" , "It drains" , "Underground drain" .)

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

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