Supports or reinforces (8)
I believe the answer is:
bolsters
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">supports</span>' is the first definition.<br/ ><span class="explanation-format__explanation">('bolster' can be a synonym of 'support')</span><br/ ><br/ >'<span class="explanation-format__original">reinforces</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(bolstering is a kind of reinforcing)</span><br/ ><br/ ></span>
(Other definitions for bolsters that I've seen before include "Long pillows or supports for lobsters" , "Supports and strengthens, props up" , "Supports with big pillows" , "Long under-pillows" .)