The most common and most likely answer to this crossword clue is the 6 letter word CLAMMY
I've seen this crossword clue in The Times
C
L
A
M
M
Y
Buddy explains!
The straight part
We know that "Warm and moist/like some marine life" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case warm and moist/like some marine life = clammy.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 CLAMMY mean?
CLAMMY adjective- Cold and damp, usually referring to hands or palms.
- The quality of normal skin signs, epidermis that is neither diaphoretic nor dry.