Cloudburst, deluge (8)
I believe the answer is:
downpour
This clue is a double definition.
'cloudburst' is the first definition.
(I know that cloudburst can be written as downpour)
'deluge' is the second definition.
(I know that deluge can be written as downpour)
(Other definitions for downpour that I've seen before include "cats and dogs?" , "Heavy continuous rainfall" , "Deluge" , "Torrent" , "Now proud (anag)" .)