Diagonal cross (7)
I believe the answer is:
saltire
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">diagonal cross</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 saltire that I've seen before include "flag - 8's? [SAINT ANDREW]" , "X-shaped cross" , "The Scottish flag" , "Cross like St Andrew's" , "Scottish cross" .)