Design plate on flower part (5)
I believe the answer is:
petal
'flower part' is the definition.
(I've seen this in another clue)
'design plate' is the wordplay.
'design' indicates anagramming the letters.
'plate' with letters rearranged gives 'PETAL'.
'on' acts as a link.
(Other definitions for petal that I've seen before include "Small seal set in a ring" , "Bloom's part" , "part taken from stock?" , "Floral leaf" , "A bit of a bloomer" .)