It offers round trips at sea (9)

I believe the answer is:

whirlpool

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'it offers round trips at sea' is the definition.
The definition suggests a singular noun which matches the answer.

This is the entire clue.

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(Other definitions for whirlpool that I've seen before include "Powerful circular current of water" , "Violent circular eddy of water" , "Strong circular current" , "Quickly rotating mass of water" .)

I've seen this clue in The Daily Mail.

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