Source of water? Fancy that! (4)

I believe the answer is:

well

I believe this is a double definition.

'source of water?' is the first definition.
(water may come from a well)

'fancy that' is the second definition.
(both are exclamations of surprise)

(Other definitions for well that I've seen before include "Healthy - water supply" , "Very much; plentiful source or supply" , "Blooming" , "Spring serving as source of water" , "The - at the World's End (William Morris)" .)

I've seen this clue in The Times.

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