Fellows from the East captivated by superb flower (7)
I believe the answer is:
anemone
'flower' is the definition.
(anemone is a kind of flower)
'fellows from the east captivated by superb' is the wordplay.
'fellows' becomes 'men' (I've seen this before).
'from the east' is a reversal indicator.
'captivated by' is an insertion indicator.
'superb' becomes 'aone' (A1).
'men' in reverse letter order is 'nem'.
'nem' going inside 'aone' is 'ANEMONE'.
(Other definitions for anemone that I've seen before include "Flower; marine polyp" , "Flower related to the buttercup" , "climbing plant" , "Woodland plant - marine polyps" , "perennial" .)