Sentence:  One day when he attended a war memorial ceremony in Westminster Abbey his view was obstructed by a stout man on his left , his attention turned to the irregular pattern of the rough slab flooring and someone , <WSD>clasping</WSD> him by the arm , whispered , `` I want a word with you , please '' . 
Meaning of the word marked with <WSD> tags:  hold firmly and tightly