The most common and most likely answer to this crossword clue is the 3 letter word UTE
U
T
E
Buddy explains!
The straight part
We know that "truck" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case truck = ute.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 UTE mean?
UTE noun- A small vehicle based on the same platform as a family car but with a unibody construction and a built-in open tray area for carrying goods; similar but not identical to a pick-up truck.