The most common and most likely answer to this crossword clue is the 3 plus 5 letter word SEA EAGLE
I've seen this crossword clue in The Times
S
E
A
E
A
G
L
E
More clues leading to the result SEA EAGLE
Buddy explains!

The straight part
We know that "predator" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case predator = sea eagle.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 SEA EAGLE mean?
SEA EAGLE noun- An eagle with a distinctive white tail; specifically, the white-tailed eagle (Haliaeetus albicilla).
- A genus of eagles (genus Haliaeetus).