The most common and most likely answer to this crossword clue is the 8 letter word AVERSIVE
I've seen this crossword clue in The Guardian
A
V
E
R
S
I
V
E
Buddy explains!

The straight part
We know that "Putting off" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case putting off = aversive.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 AVERSIVE mean?
AVERSIVE noun- (grammar) a grammatical case indicating that something is avoided or feared; the evitative case
- An unpleasant stimulus intended to induce a change in behaviour
- Tending to repel, causing avoidance (of a situation, a behaviour, an item, etc.)