Very cold in talk-back. That's repulsive (4)
I believe the answer is:
icky
'repulsive' is the definition.
(I've seen this before)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for icky that I've seen before include "Nasty, unpleasant (colloq.)" , "Cloying -- repulsive" , "Very bad" , "Repulsive - distasteful" , "Revolting" .)