The most common and most likely answer to this crossword clue is the 8 letter word TIPSTERS
I've seen this crossword clue in The Guardian
T
I
P
S
T
E
R
S
Buddy explains!
The straight part
We know that "They help gamblers" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case they help gamblers = tipsters.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 TIPSTERS mean?
TIPSTERS noun- A person who provides tips or advice to others, for example on the form of racehorses or the stock market.
- One who provides tips or hints on how to succeed at a game.