Famous tank engine (6)
I believe the answer is:
thomas
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">famous tank engine</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is the entire clue.<br/ ></span>
(Other definitions for thomas that I've seen before include "Ancient writing instruments" , "Dylan --; -- Edison" , "Doubter - tank engine" , "The Blue Boy painter, d. 1788" , "Dylan ..., ... Aquinas" .)