The most common and most likely answer to this crossword clue is the 6 letter word ANTLER
I've seen this crossword clue in The Times
A
N
T
L
E
R
More clues leading to the result ANTLER
- Learnt to play the horn
- Horn featured in middle sections of frantic boleros
- Horn covering obscuring male rhino’s head
- Rental impossible, one seen in a rut?
- Learnt about feature of some animals
- Part of crown that’s leant uneasily on king
- Head branch rental adjusted
- Bone structure can be learnt
- Dismantle reins restricting part of Rudolph?
- Somehow learnt part of Rudolph
Buddy explains!

The straight part
We know that "horn" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case horn = antler.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 ANTLER mean?
ANTLER noun- A branching and bony structure on the head of deer, moose and elk, normally in pairs. They are grown and shed each year. (Compare with horn, which is generally not shed.)