The most common and most likely answer to this crossword clue is the 12 letter word FIREFIGHTING
I've seen this crossword clue in Financial Times
F
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F
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Buddy explains!
The straight part
We know that "dowser’s job" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case dowser’s job = firefighting.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 FIREFIGHTING mean?
FIREFIGHTING noun- Extinguishing a fire.
- The profession of being a firefighter.
- (by extension) Solving an urgent problem.