Kind of medication from doctor initially in control (6)
I believe the answer is:
powder
'kind of medication' is the definition.
(I know that powder is a type of medicament)
'doctor initially in control' is the wordplay.
'initially' says to take the initial letters.
'in' is an insertion indicator.
'control' becomes 'power' (I've seen this before).
The initial letter of 'doctor' is 'd'.
'd' inserted within 'power' is 'POWDER'.
'from' is the link.
(Other definitions for powder that I've seen before include "Beauty aid" , "secured by a magazine" , "Pulverise" , "Solid substance in tiny loose particles" , "Small loose particles" .)