Talk up a storm (3)
I believe the answer is:
yak
'talk up a storm' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for yak that I've seen before include "Talk incessantly" , "Long-haired ox of central Asia" , "Beast of burden" , "Blabber" , "A Tibetan long-haired ox" .)