Despot’s drug left for later time (6)
I believe the answer is:
stalin
'despot's' is the definition.
(Joseph Stalin)
'drug left for later time' is the wordplay.
I cannot really see how this works, but
'left' could be 'l' (common abbreviation) and 'l' is present in the answer.
'time' could be 't' (abbreviation) and 't' is found within the answer.
The remaining letters 'sain' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for stalin that I've seen before include "Former Soviet leader" , "Communist dictator" , "Notorious dictator of Latins" , "Russian WW2 dictator" , "Tyrant among Latins" .)