Capricious; unreliable (6)
I believe the answer is:
fickle
<span class="explanation-format__ClueExplanation">This clue is a double definition.<br/ ><br/ >'<span class="explanation-format__original">capricious</span>' is the first definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >'<span class="explanation-format__original">unreliable</span>' is the second definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ ></span>
(Other definitions for fickle that I've seen before include "Unreliable" , "Erratic, unpredictable" , "Inconstant, changeable" , "Often changing, not constant or loyal" , "Prone to shifting loyalties" .)