The most common and most likely answer to this crossword clue is the 8 letter word DEEP-SEA
I've seen this crossword clue in The Times
D
E
E
P
-
S
E
A
More clues leading to the result DEEP-SEA
- Bass note heard in the remotest ocean?
- Pace picked up, with each occupying certain trenches?
- A European expedition held up relating to some trawling?
- . River with poster that’s never even got onto a sort of fishing
- Hurry back by mid-year giving description of wet area
- Rush up to each submarine zone
- Both sides in advance, speed goes up in the middle of the ocean
Buddy explains!

The straight part
We know that "certain trenches?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case certain trenches? = deep-sea.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 DEEP-SEA mean?
DEEP-SEA adjective- Of, related to or located in the deeper part of the sea
- (sport fishing) of or related to open sea
- (of a port) able to accommodate the largest ships.