Changing diet, Alec's fragile (8)
I believe the answer is:
delicate
'fragile' is the definition.
('delicate' can be a synonym of 'fragile')
'changing diet alec's' is the wordplay.
'changing' indicates an anagram.
'diet'+'alec'='dietalec'
'dietalec' is an anagram of 'DELICATE'.
(Other definitions for delicate that I've seen before include "Very fine or easily broken" , "Very fine; intricate" , "Dainty - fragile" , "Fine and dainty" , "Soft" .)