Knowledgeable about water sources?
I believe the answer is:
well-informed
'sources?' is the definition.
The definition and answer are not the same part of speech.
'knowledgeable about water' is the wordplay.
'knowledgeable' becomes 'informed' ('informed' can be similar in meaning to 'knowledgeable').
'about' is a charade indicator (letters next to each other).
'water' becomes 'well' (well water is a kind of water**).
'informed' put after 'well' is 'WELL-INFORMED'.
Can you help me to learn more?
(Another definition for well-informed that I've seen is " Knowing the latest".)