Radical doctor caught swigging wine (7)
I believe the answer is:
drastic
'radical' is the definition.
(I've seen this before)
'doctor caught swigging wine' is the wordplay.
'doctor' becomes 'dr' ('Dr' can be a synonym of 'doctor').
'caught' becomes 'c' (cricket abbreviation).
'swigging' is an insertion indicator.
'wine' becomes 'asti' (I've seen this before).
'dr'+'c'='drc'
'drc' enclosing 'asti' is 'DRASTIC'.
(Other definitions for drastic that I've seen before include "Harsh, severe" , "Draconian" , "Extreme - forceful" , "Grave" , "Violent Doctor Crippen starts drinking wine" .)