From Longman Dictionary of Contemporary Englishheadlockhead‧lock /ˈhedlɒk $ -lɑːk/ noun [countable] DSOHOLDa way of holding someone around their neck so that they cannot move His opponent had him in a headlock.
Examples from the Corpus
headlock• Highlights here was jan Molby giving Speed a headlock and rub of the new haircut, and Wallace being substituted. 