Water down (6)
'water down' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for dilute that I've seen before include "Weaken by adding water" , "Add liquid to lessen strength" , "having less concentration" , "Adulterate" , "Reduce concentration of a liquid" .)
'water down' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for attenuate that I've seen before include "become weak" , "Reduce (a signal)" , "Reduced" , "get thin" , "Reduce in strength" .)