The most common and most likely answer to this crossword clue is the 4 letter word MAIN
M
A
I
N
More clues leading to the result MAIN
- Answer in half minute: pipe
- Deep source of power, perhaps
- Great fighting cocks
- Principal place supplying water
- Extensive head of hair, we’re told
- Principal writer on La Rive Gauche?
- Chief and the old woman at home
- Principal sea area off Ireland, not large
- Principal game of chance
- Finally acclaim own Scottish chief
Buddy explains!

The straight part
We know that "Ocean" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case ocean = main.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 MAIN mean?
MAIN verb- Short for mainline.
- To mainly play a specific character, or side, during a game.
- Of a road: to convert into a main or primary road.
- Of chief or leading importance; prime, principal.
- Chief, most important, or principal in extent, size, or strength; consisting of the largest part.
- (of force, strength, etc.) Full, sheer, undivided.
- Big; angry.
- Belonging to or connected with the principal mast in a vessel.
- Great in size or degree; important, powerful, strong, vast.
- Exceedingly, extremely, greatly, mightily, very, very much.
- That which is chief or principal; the chief or main portion; the bulk, the greater part, gross.
- A large cable or pipe providing utility service to an area or a building, such as a water main or electric main.
- Short for main course.
- The high seas.
- The mainland.
- Short for mainsail.
- (except in might and main) Force, power, strength, violent effort.
- A hand or match in a game of dice.
- The largest throw in a match at dice; in the game of hazard, a number from one to nine called out by a person before the dice are thrown.
- A stake played for at dice.
- A sporting contest or match, especially a cockfighting match.
- A banker's shovel for coins.
- A basket for gathering grapes.