Referee’s item (3,4)
(Other definitions for red card that I've seen before include "Football punishment" , "It signals a serious rule infringement" , "Referee's sanction" , "Sending-off signal?" , "sign of dismissal" .)
(Other definitions for yellow card that I've seen before include "With which a referee cautions player" , "Warning leading to temporary dismissal" , "Warning to footballers" , "Footballer's caution" , "Warning to footballer" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">referee's item</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for whistle that I've seen before include "Make a high-pitched noise by blowing air" , "Musical with Hayley Mills" , "Instrument that's sometimes piercing" , "Pucker up and blow" , "Call vainly for" .)