The most common and most likely answer to this crossword clue is the 4 letter word ZANY
I've seen this crossword clue in The Times
Z
A
N
Y
More clues leading to the result ZANY
- Last letter by a New York eccentric
- Endearingly funny series of Tarzan? Yes
- Crazy last letter by no one in particular
- . Oddly comical sample of Tarzan yell
- Axes keep paint evenly off the wall
- Mad as the last one, the one before last
- Knight lying down, perhaps, with some old clown
- Unknown, some screwball
- Unknown character, to some extent eccentric
- Eccentric city supporting South Africa
Buddy explains!

The straight part
We know that "Endearingly funny" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case endearingly funny = zany.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 ZANY mean?
ZANY noun- A fool or clown, especially one whose business on the stage is to imitate foolishly the actions of the principal clown.
- To mimic foolishly.
- Unusual and awkward in a funny, comical manner; outlandish; clownish.
- Ludicrously or incongruously comical.