Shower unit? (8)
I believe the answer is:
raindrop
'shower unit?' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for raindrop that I've seen before include "Little evidence of wet weather" , "marks start of downfall?" , "Bit of precipitation" , "Bit of a shower?" , "One of many in a shower" .)