The most common and most likely answer to this crossword clue is the 3 letter word HOD
I've seen this crossword clue in The Daily Telegraph
H
O
D
Buddy explains!

The straight part
We know that "Carrier" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case carrier = hod.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 HOD mean?
HOD verb- To bob up and down on horseback; jog.
- A three-sided box for carrying bricks or other construction materials, often mortar. It bears a long handle and is carried over the shoulder.
- A receptacle for carrying coal, particularly one designed to facilitate loading coal or coke through the door of a firebox.
- A pewterer's blowpipe.
- A bookmaker's bag.