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

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 DAN mean?
DAN noun- A title of honour similar to "master" or "father", used of historical and legendary figures of the past.
- A small truck or sledge used in coal mines.
- A rank of black belt in martial arts
- Someone who has achieved a level of black belt
- A traditional South and East Asian unit of weight, based upon the load of a shoulder pole and varying by place and over time but usually standardized at about 60 kg.