Strikes; criticises (6)
I believe the answer is:
knocks
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">strikes</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(knocking is a kind of striking)</span><br/ ><br/ >'<span class="explanation-format__original">criticises</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I know this)</span><br/ ><br/ ></span>
(Other definitions for knocks that I've seen before include "You get bad experiences in the school of hard ..." , "Bangs on door" , "Hits" , "Reversals" , "Strikes with a sharp blow or finds fault with" .)