Could be a flute or a balloon (5)
I believe the answer is:
glass
'a balloon' is the definition.
The definition and answer can be both man-made objects as well as being singular nouns.
Maybe there's an association between them I don't understand?
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for glass that I've seen before include "such as one might hold at party" , "Brittle transparent material" , "(Material used in) mirror" , "Transparent stuff" , "that one can see through" .)