The most common and most likely answer to this crossword clue is the 5 letter word ALOOF
I've seen this crossword clue in The Guardian
A
L
O
O
F
More clues leading to the result ALOOF
- A pudding sent back cold
- A mug served up cold
- Cold potato? Fine
- A pudding sent up cold?
- Withdrawn dessert, American upset
- Reserved area idiot rejected
- Unpleasantly cold, a roly-poly pudding
- Unfriendly, when a clown shows up
- A place to go with female that’s pretty distant
- A jester, revolting and supercilious
Buddy explains!

The straight part
We know that "Unfriendly" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case unfriendly = aloof.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 ALOOF mean?
ALOOF adjective- Reserved and remote; either physically or emotionally distant; standoffish.
- At or from a distance, but within view, or at a small distance; apart; away.
- Without sympathy; unfavorably.
- Away from; clear of.