Dissatisfied agent not yet retired? (3,2)
I believe the answer is:
fed up
'dissatisfied' is the definition.
(I've seen this before)
'agent not yet retired?' is the wordplay.
'agent' becomes 'fed' (fed is a kind of agent).
'not yet retired?' becomes 'up' (not yet gone to bed).
'fed'+'up'='FED UP'
(Other definitions for fed up that I've seen before include "Hacked off" , "Surfeited" , "Disgruntled (colloq.)" , "like infant in high chair?" , "Dissatisfied" .)