Remove sediment from port? (6)

I believe the answer is:

dredge

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'remove' is the definition.
(I know that dredge is a more specific form of the action remove)

I can't explain the remainder of the clue.

Can you help me to learn more?

(Other definitions for dredge that I've seen before include "digging equipment" , "Scoop mud from, say, harbour" , "Remove mud from a riverbed" , "Scrape up material from sea bed" , "Clean out (mud) from channel" .)

I've seen this clue in The Sun.

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