Subtle changes creating a stir (6)
I believe the answer is:
bustle
'a stir' is the definition.
('bustle' can be a synonym of 'stir')
'subtle changes' is the wordplay.
'changes' is an anagram indicator.
'subtle' anagrammed gives 'BUSTLE'.
'creating' is the link.
(Other definitions for bustle that I've seen before include "Busy oneself noisily about the former feature of women's dress" , "Frame under a dress" , "Scurry - frame worn under skirt" , "Energetic activity" , "Subtle kind of hubbub" .)