The most common and most likely answer to this crossword clue is the 4 letter word TWIG
I've seen this crossword clue in The Times
T
W
I
G
More clues leading to the result TWIG
Buddy explains!
The straight part
We know that "Cotton on/branch in tree" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case cotton on/branch in tree = twig.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 TWIG mean?
TWIG noun- A small thin branch of a tree or bush.
- To beat with twigs.
- To realise something; to catch on; to recognize someone or something.
- To understand the meaning of (a person); to comprehend.
- To observe slyly; also, to perceive; to discover.
- To twitch; to pull; to tweak.