Commit foul — dismissed before full time (6)
I believe the answer is:
offend
'commit' is the definition.
(thesaurus)
I don't understand the rest of the clue.
Can you help me to learn more?
(Other definitions for offend that I've seen before include "Affront - break the law" , "Cause displeasure or hurt, be nasty towards" , "Hurt someone's feelings" , "tread on someone's toes?" , "Insult - act criminally" .)