Prison officer (6)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">prison officer</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for warder that I've seen before include "screw" , "Prison officer" , "Reward for prison guard" , "One is in charge of prisoners" , "Jailer" .)
(Other definitions for warden that I've seen before include "Guard, keeper" , "Prison or traffic official" , "Head of certain schools, colleges, etc" , "Custodian" , "Person in charge (of traffic etc)" .)