Refreshing drinks cat, I see, has upset (3,4)
I believe the answer is:
Here is my best explanation:
'refreshing drinks' is the definition.
'cat i see has upset' is the subsidiary indication.
'has upset' indicates anagramming the letters.
'catisee' with letters rearranged gives 'iceteas'.
(Other definitions for ice teas that I've seen before include "Cold drinks" and "refreshment for many - with 12a".)