The most common and most likely answer to this crossword clue is the 6 letter word FULMAR
I've seen this crossword clue in Financial Times
F
U
L
M
A
R
More clues leading to the result FULMAR
- Portion of flavourful marine bird
- Seabird needed by grateful mariner
- Seabird left mother when covered with hairy coat
- Oceanic bird saved by resourceful marine
- Bird has a long way to go round German city
- Bird has some colourful markings
- Seabird mostly stuffed with butter that’s turned
- Bird identified by some beautiful markings
- Some powerful maritime bird
- Seabird spotted in wonderful Margate
Buddy explains!

The straight part
We know that "Oceanic bird" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case oceanic bird = fulmar.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.
Crossword Answer definitions
FULMAR noun- Either of two species of pelagic seabird in the genus Fulmarus, Fulmarus glacialis and F. glacialoides, which breed on cliffs.