Gratis, free of charge (13)
I believe the answer is:
complimentary
<span class="explanation-format__ClueExplanation">I believe this clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">gratis</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >'<span class="explanation-format__original">free of charge</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(thesaurus)</span><br/ ><br/ ></span>
(Other definitions for complimentary that I've seen before include "Free (ticket); praising" , "Clammy pointer (anag) - costing nothing" , "Given free" , "Adulatory - gratis" , "Expressing approval - not to be paid for" .)