Fine source of water (4)
I believe the answer is:
well
I believe this is a double definition.
'fine' is the first definition.
(similar in meaning)
'source of water' is the second definition.
(I've seen this before)
(Other definitions for well that I've seen before include "four-letter word repeated in Shakespeare comedy" , "31 [SPRING]" , "Source; in good health" , "Sound" , "Cockpit" .)