The most common and most likely answer to this crossword clue is the 9 letter word ISINGLASS
I've seen this crossword clue in The Times
I
S
I
N
G
L
A
S
S
More clues leading to the result ISINGLASS
- I’m a vocalist, love — something fishy here
- Fishy product gets stored by schooner, say
- Product of the sea becomes ready to drink?
- Fishy stuff indicating location of one's tipple?
- Gelatinous substance in abandoned sailing ship
- Fish product is ready to drink?
- Gelatine is in drinking vessel
- A powder: one in tumbler son swallowed?
- Brummie squeals “Miss Gelatine”
- Fishy product occupies schooner, say
Buddy explains!
The straight part
We know that "Product of the sea" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case product of the sea = isinglass.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 ISINGLASS mean?
ISINGLASS noun- A form of gelatine obtained from the air bladder of the sturgeon and certain other fish, used as an adhesive and as a clarifying agent for wine and beer.
- A thin, transparent sheet of mica (probably from its similarity to true isinglass).