Experienced person that's horrible must retire (5)
I believe the answer is:
lived
'experienced' is the definition.
(living is a kind of experiencing)
'person that's horrible must retire' is the wordplay.
'person that's horrible' becomes 'devil'.
'must retire' shows that the letters should be reversed in order.
'devil' in reverse letter order is 'LIVED'.
(Other definitions for lived that I've seen before include "Existed or dwelt" , "Escaped destruction" .)