Dragon killed by Apollo at Delphi (6)
I believe the answer is:
python
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">dragon killed by apollo at delphi</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this before)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for python that I've seen before include "crawler" , "Type of snake" , "Large snake that crushes and swallows its prey" , "Large non-venomous snake" , "Heavy-bodied snake" .)