Floating Delta ice is likely to break (8)
I believe the answer is:
Here is my best explanation:
'likely to break' is the definition.
I can't judge whether this defines the answer.
'floating delta ice' is the subsidiary indication.
'floating' is an anagram indicator (float can mean fluctuate or oscillate).
'deltaice' anagrammed gives 'delicate'.
'is' is the link.
(Other definitions for delicate that I've seen before include "Exquisite; needing tactful handling", "Fine in texture", "Exquisitely fine and subtle", "ticklish!", "Very finely textured", "Exquisitely fine, easily damaged", "Very fine or easily broken", "Weak", "Easily damaged" and "Flimsy".)