Actor Astin (4)
I believe the answer is:
sean
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">actor astin</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 sean that I've seen before include "- - Connery (007)" , "guy at Number 10 [IRISHMAN]" , "Penn, Bean or O'Casey" , "Irish form of John" .)