Not great changes according to plan (2,6)
I believe the answer is:
on target
'according to plan' is the definition.
'not great changes' is the wordplay.
'changes' is an anagram indicator.
'not'+'great'='notgreat'
'notgreat' with letters rearranged gives 'ON TARGET'.
(Other definitions for on target that I've seen before include "Accurate (shot)" , "Heading in the right direction" , "Where bull may be" , "Keeping to a course" , "Up to the planned level" .)