Crazy leader of dissidents exploded grenade (8)
I believe the answer is:
deranged
'crazy' is the definition.
(thesaurus)
'leader of dissidents exploded grenade' is the wordplay.
'leader of' suggests taking the first letters.
'exploded' indicates anagramming the letters.
The initial letter of 'dissidents' is 'd'.
'grenade' is an anagram of 'eranged'.
'd'+'eranged'='DERANGED'
(Other definitions for deranged that I've seen before include "totally without reason" , "Crackpot" , "irrational" , "Disordered; insane" , "Made insane" .)