Exclamation of surprise with herb appearing in floral arrangement (7)
I believe the answer is:
corsage
'floral arrangement' is the definition.
(arrangement of flowers worn on clothing)
'exclamation of surprise with herb' is the wordplay.
'exclamation of surprise' becomes 'cor' (expression of surprise).
'with' means one lot of letters go next to another.
'herb' becomes 'sage' (sage is a kind of herb).
'cor'+'sage'='CORSAGE'
'appearing in' acts as a link.
(Other definitions for corsage that I've seen before include "Flowers pinned to dress" , "Flower worn on bodice" , "Spray of flowers" , "Sort of bouquet" , "Nosegay, posy" .)