Nudge 1: Considering the theme is "The Sea" there sure isn't much about the sea in this puzzle
Nudge 2: Maybe all mentions of the theme have been deliberately omitted
Nudge 3: So put the mentions back in....
Nudge 4: It's a meta. So go meta-ing.
Nudge 5: You have a five letter word.
Nudge 6: That five letter word is like the first words of the clues of the meta themers.
Nudge 7: The answer to this meta is an entry that really should have had a clue that fit the theme like the other five meta related entries but didn't.
If you come up with a creative alternate solution, I may be generous and accept it