Circle inside part of a flower is different (7)
I believe the answer is:
another
'different' is the definition.
('another' can be a synonym of 'different')
'circle inside part of a flower' is the wordplay.
'circle' becomes 'o'.
'inside' is an insertion indicator.
'part of a flower' becomes 'anther' ('anther' is part of 'flower').
'o' placed into 'anther' is 'ANOTHER'.
'is' is the link.
(Other definitions for another that I've seen before include "Additional, one more" , "Player or person not yet named or selected" , "A further (item)" , "encore?" , "Someone else" .)