The most common and most likely answer to this crossword clue is the 6 letter word GIBBON
I've seen this crossword clue in The Guardian
G
I
B
B
O
N
More clues leading to the result GIBBON
- Forest dweller turning elephantine head around
- Ape an old historian
- In circulation, not a single book by great historian
- Ape - giant turning up with bone, shortly
- Historian, a big swinger
- Ape/baboon regularly caught in trap
- Ape a historian
- Great upset over book about ape
- Ignoring following, fobbing off historian
- Primate and historian
Buddy explains!

The straight part
We know that "Ape/historian" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ape/historian = gibbon.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 GIBBON mean?
GIBBON noun- A small ape of the family Hylobatidae with long limbs, which it uses to travel through rainforests by swinging from branch to branch.