The most common and most likely answer to this crossword clue is the 6 letter word MUCKER
I've seen this crossword clue in The Daily Telegraph
M
U
C
K
E
R
More clues leading to the result MUCKER
Buddy explains!

The straight part
We know that "Friend" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case friend = mucker.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 MUCKER mean?
MUCKER noun- (Southern England) friend, acquaintance
- (British army) A comrade; a friendly, low-ranking soldier in the same situation.
- A person who removes muck (waste, debris, broken rock, etc.), especially from a mine, construction site, or stable.
- A low or vulgar labourer.
- To scrape together (money, etc.) by mean labour or shifts.