Accidentally (2,6)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">accidentally</span>' is the definition.<br/ ><span class="explanation-format__explanation">(synonyms)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for by chance that I've seen before include "unwittingly" , "Accidentally, not planned" , "Unplanned, as it happened" , "Without advance planning" , "Fortuitously" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">accidentally</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>