This is very easy to obtain at the start of the game.
During the quest '
Lilacs & Gooseberries', you are hunting for Yennefer. After encountering the unlucky Merchant, you end up in the local tavern.
You can talk to a Scholar to learn the basics of the cardgame gwent.
Upon leaving, there are 3 locals who dislike Witchers, and accost you.
I chose the dialogue option to cast a sign and 'daze' one of them - the other 2 leap in,
and it is here that you are in the fist-fight.
Quickly tap 
to land a fast strike on one - he goes out in 1 punch, the trophy will unlock immediately.