Cloudburst (4)
'cloudburst' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for downpour that I've seen before include "Cloudburst" , "Heavy fall of rain" , "Now proud (anag)" , "Heavy shower" , "Heavy continuous rainfall" .)
'cloudburst' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for rain that I've seen before include "Precipitation" , "See 12" , "Storm" , "Pelt" , "Cats and dogs?" .)