The most common and most likely answer to this crossword clue is the 8 letter word FRIENDLY
I've seen this crossword clue in Financial Times
F
R
I
E
N
D
L
Y
More clues leading to the result FRIENDLY
- Warm soup's unwelcome visitor diner anxiously pokes
- Congenial diner fly worried
- Diner travelling in carriage prepared to talk to fellow passengers?
- Amiable lady disheartened by Friday finish
- China may be thus, or Tonga’s islands?
- Amiable, and at close of day extremely lively
- Favourable directions in force, delivered extremely loftily
- Intimate brief fling with Ryde deviant
- . Kind of insect outside bothered diner
- Avuncular cook, trousers tailored, lined
Buddy explains!

The straight part
We know that "Avuncular" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case avuncular = friendly.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 FRIENDLY mean?
FRIENDLY noun- A game which is of no consequence in terms of ranking, betting etc.
- A person or entity on the same side in a conflict.
- Generally warm, approachable and easy to relate with in character.
- Inviting, characteristic of friendliness.
- Having an easy or accepting relationship with something.
- Without any hostility.
- Promoting the good of any person; favourable; propitious.
- Of or pertaining to friendlies (friendly noun sense 2, below). Also applied to other bipolar confrontations, such as team sports
- Being or relating to two or more natural numbers with a common abundancy.
- (in compounds) Compatible with, or not damaging to (the compounded noun).
- In a friendly manner, like a friend.