Plant has woman in nursery full of bombast (8)
I believe the answer is:
amaranth
'plant' is the definition.
(amaranth is a kind of plant)
'woman in nursery full of bombast' is the wordplay.
'woman in nursery' becomes 'amah'.
'full of' means one lot of letters goes inside another.
'bombast' becomes 'rant' (synonyms).
'amah' enclosing 'rant' is 'AMARANTH'.
'has' acts as a link.
(Other definitions for amaranth that I've seen before include "Edible plant; purple" , "Never-fading flower; food colour dye" , "Type of cereal" , "tropical plant" , "Fabled never-fading flower" .)