Sacking personnel extremely ready for operation? (7)
I believe the answer is:
plunder
'sacking' is the definition.
(thesaurus)
'personnel extremely ready for operation?' is the wordplay.
'extremely' suggests removing the centre.
'ready for operation?' becomes 'under' (I can't explain this - if you can you should believe this answer much more).
'personnel' with its centre taken out is 'pl'.
'pl'+'under'='PLUNDER'
Can you help me to learn more?
(Other definitions for plunder that I've seen before include "Take as spoils" , "Ransack" , "Stolen or looted goods" , "Forcibly stolen property" , "Loot" .)