Son tried changing step (6)
I believe the answer is:
stride
'step' is the definition.
(I know that stride is a type of step)
'son tried changing' is the wordplay.
'son' becomes 's' (genealogical abbreviation for son).
'changing' indicates an anagram.
'tried' anagrammed gives 'tride'.
's'+'tride'='STRIDE'
(Other definitions for stride that I've seen before include "A lengthy step" , "Take long paces" , "Extended footstep" , "Long step of direst kind" , "Take long steps" .)