The most common and most likely answer to this crossword clue is the 3 plus 3 plus 3 plus 4 letter word ONE FOR THE ROAD
I've seen this crossword clue in The Guardian
O
N
E
F
O
R
T
H
E
R
O
A
D
More clues leading to the result ONE FOR THE ROAD
- A supporter of motorway development? It takes some swallowing finally
- Moving on to Hereford, a final pint downed?
- Hopefully this won’t get you Knocked Out Loaded before Highway 61 Revisited
- Last order from hero often misrepresented on course
- Drink before leaving stone fort hero adventurer sampled
- Parting shot, not desirable in any way
Buddy explains!

The straight part
We know that "Last order/Last order" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case last order/last order = one for the road.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.