Angry about IT after computer's last bug (8)
I believe the answer is:
irritate
'bug' is the definition.
(I know this)
'angry about it after computer's last' is the wordplay.
'angry' becomes 'irate' (irate can mean angry or annoyed).
'about it' indicates putting letters inside.
'after computer's last' becomes 'rit' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'irate' going around 'rit' is 'IRRITATE'.
Can you help me to learn more?
(Other definitions for irritate that I've seen before include "Nark" , "bug" , "badger" , "Anger, annoy" , "'Annoy, vex (8)'" .)