Good source of water (4)

I believe the answer is:

well

I believe this is a double definition.

'good' is the first definition.
(synonyms)

'source of water' is the second definition.
(I've seen this before)

(Other definitions for well that I've seen before include "Issue forth" , "Spring - in good condition" , "31 [SPRING]" , "Competently" , "Fine - drilled hole" .)

I've seen this clue in The Sunday Times.

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