Good-for-nothing doctor working with little energy (5)
I believe the answer is:
drone
'good-for-nothing' is the definition.
(drone can mean a lazy person)
'doctor working with little energy' is the wordplay.
'doctor' becomes 'dr' (abbreviation).
'working' becomes 'on' (e.g. a machine is working or on).
'with' means one lot of letters go next to another.
'little' suggests taking the first letters.
The initial letter of 'energy' is 'e'.
'dr'+'on'+'e'='DRONE'
(Other definitions for drone that I've seen before include "Queen bee1s mate" , "small creature" , "he gives us a buzz" , "talk long and tediously" , "Idle fellow" .)