One vessel on which another may be stood (7)

I believe the answer is:

coaster

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'one vessel' is the definition.
(I've seen this before)

I can't explain the remainder of the clue.

(Other definitions for coaster that I've seen before include "Small mat for glass" , "Ship; (drinks) mat" , "Tray; trader" , "It goes under a schooner, perhaps" , "proceeds with little effort" .)

I've seen this clue in the Evening Standard.

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