Doubting apostle (6)
I believe the answer is:
thomas
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">doubting apostle</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for thomas that I've seen before include "One of the Twelve Apostles" , "Famous tank engine" , "The Apostle who initially doubted the Resurrection" , "He had doubts" , "He needs convincing" .)