Infamous old buggers just as idiotic at heart (5)
I believe the answer is:
stasi
'infamous old buggers' is the definition.
I know nothing about this answer so I can't tell whether this works.
'just as idiotic at heart' is the wordplay.
'at heart' says the answer is hidden in the clue (letters hidden in the heart of the clue).
'STASI' can be found hidden inside 'just as idiotic'.
Can you help me to learn more?
(Other definitions for stasi that I've seen before include "Former German security service" , "Force that spied" , "old secret service" , "Former security force" , "Force behind Wall" .)