The most common and most likely answer to this crossword clue is the 7 letter word ICEBERG
I've seen this crossword clue in The Times
I
C
E
B
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More clues leading to the result ICEBERG
- I caught diver’s upturned frozen body
- Cold and unemotional type in charge, diver recalled
- I caught bird around frozen mass of water
- Sort of lettuce you see little of in the main
- Titanic hit this, one church composer put together
- I caught bird that's pulled up lettuce
- Recalled diving bird going behind one cold Arctic feature
- One cold diver turns over chunk of glacier
- Lettuce, ricein salad
- I see diving bird returning to very cold water
Buddy explains!

The straight part
We know that "frozen mass of water" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case frozen mass of water = iceberg.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 ICEBERG mean?
ICEBERG noun- A huge mass of ocean-floating ice which has broken off a glacier or ice shelf
- An aloof person.
- (after an adjective) An impending disastrous event whose adverse effects are only beginning to show, in reference to one-tenth of the volume of an iceberg being visible above water.