Heather is a woman (5)
I believe the answer is:
erica
I believe this clue is a double definition.
'heather' is the first definition.
(the plant genus Erica includes heather plants)
'woman' is the second definition.
'is a' is the link.
(Other definitions for erica that I've seen before include "Plant genus of garden heather" , "Shrubs" , "I care (anag) - plant - girl" , "Girl's name - I care (anag)" , "Heather's Latin name?" .)