Flier, bird is in cold sea shaking off one cold tail! (10)

'flier' is the definition.
(I know that flier can be written as balloonist)

'bird is in cold sea shaking off one cold tail' is the wordplay.
I cannot really understand how this works, but
'bird' could be 'loon' (loon is a kind of bird) and 'loon' is found within the answer.
'is' is found in the answer.
'one' could be 'a' (a thing is one thing) and 'a' is located in the answer.
The remaining letters 'blt' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...

Can you help me to learn more?