Precursor to deluge, it was said, gun getting damp (7)
I believe the answer is:
moisten
'damp' is the definition.
(I've seen this before)
'precursor to deluge it was said gun' is the wordplay.
I cannot really see how this works, but
'it' could be 't' (abbreviation. e.g. in 'tis) and 't' is present in the answer.
'was' could be 'is' (being is a kind of being) and 'is' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
'getting' acts as a link.
Can you help me to learn more?
(Other definitions for moisten that I've seen before include "contrary to sixteen down [DEHYDRATE]!" , "What one's eyes may do!" , "Make damp or slightly wet" , "It's on me (anag)" , "Make damp, say lips with tongue" .)