Advantageous, encouraging (10)
I believe the answer is:
favourable
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">advantageous</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I know that advantageous can be written as favourable)</span><br/ ><br/ >'<span class="explanation-format__original">encouraging</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ ></span>
(Other definitions for favourable that I've seen before include "20 [GOOD]" , "Propitious" .)