One or the other rite he changed (6)
I believe the answer is:
either
'one or the other' is the definition.
(I've seen this before)
'rite he changed' is the wordplay.
'changed' is an anagram indicator.
'rite'+'he'='ritehe'
'ritehe' with letters rearranged gives 'EITHER'.
(Other definitions for either that I've seen before include "Word indicating the following alternatives" , "offered a choice" , "Her tie (anag.)" , "One of two alternatives" , "Each of two; moreover" .)