The most common and most likely answer to this crossword clue is the 7 letter word BACKERS
I've seen this crossword clue in The Daily Telegraph
B
A
C
K
E
R
S
More clues leading to the result BACKERS
Buddy explains!

The straight part
We know that "sponsors" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sponsors = backers.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 BACKERS mean?
BACKERS noun- One who, or that which, backs; especially one who backs an entrant in a contest, or who supports an enterprise by funding it.