The most common and most likely answer to this crossword clue is the 7 letter word BREWERS
I've seen this crossword clue in Independent
B
R
E
W
E
R
S
Buddy explains!

The straight part
We know that "We pay them to give us a good wallop" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case we pay them to give us a good wallop = brewers.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 BREWERS mean?
BREWERS noun- Someone who brews, or whose occupation is to prepare malt liquors.