Admit EEC prepared to destroy (8)
I believe the answer is:
decimate
'to destroy' is the definition.
(I've seen this before)
'admit eec prepared' is the wordplay.
'prepared' indicates anagramming the letters.
'admit'+'eec'='admiteec'
'admiteec' anagrammed gives 'DECIMATE'.
(Other definitions for decimate that I've seen before include "slaughter" , "Medicate (anag.)" , "By killing" , "Wipe out a large number" , "severely cut" .)