Well fed agent hired at end of June (7)
I believe the answer is:
replete
'well fed' is the definition.
(replete means full)
'agent hired at end of june' is the wordplay.
'agent' becomes 'rep' (short for representative).
'hired' becomes 'let' (I've seen this in other clues).
'at end of' says to take the final letters.
The final letter of 'june' is 'e'.
'rep'+'let'+'e'='REPLETE'
(Other definitions for replete that I've seen before include "Chock-a-block" , "Completely filled" , "Full, sated" , "Full to capacity" , "Well-fed" .)