Notices doctor returning without drug and is furious (4,3)
I believe the answer is:
sees red
'without drug and is furious' is the definition.
I can't tell whether this defines the answer.
'notices doctor returning' is the wordplay.
'notices' becomes 'sees' (I've seen this in other clues).
'doctor' becomes 'der' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'returning' says the letters should be written in reverse.
'der' reversed gives 'red'.
'sees'+'red'='SEES RED'
Can you help me to learn more?
(Another definition for sees red that I've seen is " 'Becomes colourfully angry (4,3)'".)