The most common and most likely answer to this crossword clue is the 7 letter word GEYSERS
I've seen this crossword clue in The Daily Telegraph
G
E
Y
S
E
R
S
Buddy explains!
The straight part
We know that "they spout a lot" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case they spout a lot = geysers.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 GEYSERS mean?
GEYSERS noun- A boiling natural spring which throws forth at frequent intervals jets of water, mud etc., driven up by the expansive power of steam.
- An instantaneous, and often dangerous, hot water heater.
- A domestic water boiler.