Drug a politician before he starts to trigger atomic bomb (11)
I believe the answer is:
amphetamine
'drug' is the definition.
(I know that amphetamine is a type of drug)
'a politician before he starts to trigger atomic bomb' is the wordplay.
'politician' becomes 'MP' (Member of Parliament).
'before' is a charade indicator (letters next to each other).
'starts to' says to take the initial letters.
'bomb' becomes 'mine' (I've seen this before).
The initial letters of 'trigger atomic' is 'ta'.
'a'+'mp'+'he'+'ta'+'mine'='AMPHETAMINE'
(Other definitions for amphetamine that I've seen before include "speed that's restricted by law" , "Upper" , "Mood-altering drug" , "Stimulant drug" .)