The most common and most likely answer to this crossword clue is the 6 plus 7 letter word ANIMAL KINGDOM
I've seen this crossword clue in The Guardian
A
N
I
M
A
L
K
I
N
G
D
O
M
More clues leading to the result ANIMAL KINGDOM
- A milkman doing trips for beasts in general
- Beastly collection delivered by angry mailman biting family dog — that’s back to front
- Millions will support goal mankind set protecting island fauna
- The French bird over country seeing all the wildlife
- Natural realm, in particular for large varieties of cobra, penguin and prawn?
Buddy explains!
The straight part
We know that "Natural realm/(6,7)" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case natural realm/(6,7) = animal kingdom.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.