Sorted out how clinch works and want to share this info with beginners. As it is not described in in-game help notes, might be useful for those who just started the game.

To get in a clinch you need to close the distance with your opponent which triggers clinch automatically.

To win the clinch you HAVE to press one of the attack buttons as soon as possible after getting in a clinch (main attack- LMB, peircing/alternative attack - RMB or special attack - F).

Chances of winning the clinch depend on the difference between yours and your opponent strength and perks (maybe from the type of an armor and general combat skill).

So don't think you do something wrong when you lose all clinches at the beginning. I've started to get an upper hand in some clinches when i hit 10-12 strenght and got the "Clinch Master" perk in the strength tree.

Here is the description of the possible attacks in a clinch:

Unarmed
Main - push in head with left hand
Piercing - knee kick to the head
Special - twist the elbow

Weapon with no shield
Main - kick and push
Piercing- hit with the fist/handle of a weapon
Special - push with hand

1h + Shield
Main - kick and push
Piercing- hit with the handle of a weapon
Special - hit with the fron edge of a shield