Accidentally (8)
'accidentally' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for by chance that I've seen before include "unwittingly" , "Accidentally, not planned" , "Unplanned, as it happened" , "Without advance planning" , "Fortuitously" .)
'accidentally' is the definition.
(I've seen this in another clue)
This is the entire clue.