The most common and most likely answer to this crossword clue is the 6 letter word DRIEST
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Buddy explains!

The straight part
We know that "Having less rain than anywhere else" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case having less rain than anywhere else = driest.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 DRIEST mean?
DRIEST adjective- Free from or lacking moisture.
- Unable to produce a liquid, as water, oil, or (farming) milk.
- Built without or lacking mortar.
- Anhydrous: free from or lacking water in any state, regardless of the presence of other liquids.
- Athirst, eager.
- Free from or lacking alcohol or alcoholic beverages.
- Describing an area where sales of alcoholic or strong alcoholic beverages are banned.
- Free from or lacking embellishment or sweetness, particularly:
- (somewhat derogatory) Involving computations rather than work with biological or chemical matter.
- (of a sound recording) Free from applied audio effects.
- Without a usual complement or consummation; impotent.
- Of a mass, service, or rite: involving neither consecration nor communion.