The most common and most likely answer to this crossword clue is the 4 plus 2 letter word SNAP UP
I've seen this crossword clue in Financial Times
S
N
A
P
U
P
More clues leading to the result SNAP UP
- Quickly buy drink having grabbed forty winks
- Quickly get game finished
- Quickly get ahead after game
- Bag drink, rest bottled
- Quickly buy pans suggested
- Partners seek a young animal to buy with haste
- Eagerly purchase bowls, perhaps?
- Grab a quick shot on horseback
- Game over for purchase
- Quickly grab biscuit, having got out of bed
Buddy explains!

The straight part
We know that "Quickly get" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case quickly get = snap up.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.