The most common and most likely answer to this crossword clue is the 8 letter word RAINDROP
I've seen this crossword clue in Financial Times
R
A
I
N
D
R
O
P
More clues leading to the result RAINDROP
- Artillery arriving by parachute, presumably causing a bit of a splash?
- Poor Indra somehow having nothing to release — not even this?
- Artist going down for a little water
- What developed air resistance filling muddy pond?
- River rapid on fresh bit of water
- Ignoring Duke, empty sink and part of shower
- This falls in shower and sink
- Soldiers parachuting – a bit of a shower
- Runs operation after incursion to secure new bit of water
- Element of weather, one interrupting American leisure and work
Buddy explains!

The straight part
We know that "a bit of a shower" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a bit of a shower = raindrop.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does RAINDROP mean?
RAINDROP noun- A single droplet of rainwater that has just fallen or is falling from the sky.