Crew said something at Chiswick in Boat Race (4)

I believe the answer is:

eyot

'something at chiswick in boat race' is the definition.
(Chiswick Eyot, island of the Thames)

I don't understand how the remainder of the clue works.

(Other definitions for eyot that I've seen before include "Small river island" , "Little island in a river or lake" , "isle" , "Islet found in a river, (especially in England)" , "Fawlty Towers waiter" .)

I've seen this clue in The Times.

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