Good as a source of water? (4-7)
I believe the answer is:
well-behaved
'good' is the definition.
(similar in meaning)
'a source of water?' is the wordplay.
'a source' becomes 'well' (well is a kind of source).
'of water?' becomes 'behaved' (I can't justify this - if you can you should believe this answer much more).
'well'+'behaved'='WELL-BEHAVED'
'as' is the link.
Can you help me to learn more?
(Other definitions for well-behaved that I've seen before include "Acting with decorum" , "Conducting oneself properly" , "Acting with propriety" .)