Judge a waterfall mantra (7)
I believe the answer is:
refrain
'mantra' is the definition.
The answer and definition can be both related to communication as well as being singular nouns.
Maybe you can see an association between them that I can't see?
'judge a waterfall' is the wordplay.
'judge' becomes 'ref' (referee).
'a waterfall' becomes 'rain' (rain is water falling down).
'ref'+'rain'='REFRAIN'
Can you help me to learn more?
(Other definitions for refrain that I've seen before include "Stop - chorus" , "Chorus of a song" , "Main part of song - do not do it" , "Desist, abstain" , "Do without" .)