Bloomer is top of fashion in revolution (8)
I believe the answer is:
daffodil
'bloomer' is the definition.
(I've seen this before)
'top of fashion in revolution' is the wordplay.
'top' becomes 'lid' (lid is a kind of top).
'fashion' becomes 'fad' (fad is a kind of fashion).
'in revolution' says the letters should be written backwards.
'lid'+'of'+'fad'='lidoffad'
'lidoffad' written backwards gives 'DAFFODIL'.
'is' is the link.
(Other definitions for daffodil that I've seen before include "Floral emblem of Wales" , "Type of 24 across" , ""Welsh" flower?" , "Lent lily" , "national symbol" .)