The most common and most likely answer to this crossword clue is the 3 plus 3 letter word PUT OFF
I've seen this crossword clue in Financial Times
P
U
T
O
F
F
More clues leading to the result PUT OFF
- Postpone retiring high-spirited bigwig
- Smoke rings to do later
- Advertisement going about to dissuade
- Discourage delay
- Discourage delay
- Disconcert upper-class swell turning up first
- Upper-class type turning up first is deterred
- Postpone draw? About to
- 1 by stripping Lilliput of food
- Diverted at Oxford? The reverse by Bullingdon Club type!
Buddy explains!

The straight part
We know that "Postpone" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case postpone = put off.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.