The most common and most likely answer to this crossword clue is the 4 letter word RAIN
I've seen this crossword clue in The Guardian
R
A
I
N
More clues leading to the result RAIN
- Reportedly, be in power shower
- Listening, means to check for bad weather
- Water settling in drainpipe
- Drops artist home
- Bad weather: hurried to shelter one
- A shower are in charge, we’re informed
- Resurgent Australian openers batting — what might stop them?
- God at home with warmer 21?
- Drops painter home
- With its arrival, I dashed for cover
Buddy explains!
The straight part
We know that "warmer 21" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case warmer 21 = rain.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 RAIN mean?
RAIN noun- Condensed water falling from a cloud.
- Any matter moving or falling, usually through air, and especially if liquid or otherwise figuratively identifiable with raindrops.
- An instance of particles or larger pieces of matter moving or falling through air.
- To have rain fall from the sky.
- To fall as or like rain.
- To issue (something) in large quantities.
- To reign.