With one leg on each side (9)
(Other definitions for astraddle that I've seen before include "Across" , "How the jockey wants to be" , "with legs wide apart" , "With a leg on either side of (something)" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">with one leg on each side</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 astride that I've seen before include "On the back of" , "Not side saddle" , "With one leg on either side, as sitting on horse" , "With legs stretched apart - tirades (anag)" , "With legs on each side" .)