Part of the week (7)
I believe the answer is:
tuesday
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">part of the week</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 tuesday that I've seen before include "Ruby - (The Rolling Stones)" , "Shrove ____" , "Part of week (for pancakes?)" , "forty eight hours before Chesterton's man" , "Day the Romans called the day of Mars" .)