Calyx component (5)
I believe the answer is:
sepal
'calyx component' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sepal that I've seen before include "Calyx segment" , "Part of a flower - peals (anag)" , "flowery bit" , "Enclosing part of flower" , "Part of a flower's outer envelope" .)