Very disappointed (4,2,1,6)
I believe the answer is:
sick as a parrot
'very disappointed' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for sick as a parrot that I've seen before include "Really gutted" , "Severely disappointed" , "badly gutted" , "Extremely disappointed (colloq.)" , "Awfully disappointed" .)