Chief support (8)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">chief support</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for mainstay that I've seen before include "Piece of rigging" , "Strong cable that secures a mast, chief support generally" , "Linchpin, principal support" , "Pillar of strength" , "Strongest support" .)
(Other definitions for stand-by that I've seen before include "Something kept in readiness" , "Quiescent state" .)