Tolkien monster concealed flower (6)
I believe the answer is:
orchid
'flower' is the definition.
(orchid is a kind of flower)
'tolkien monster concealed' is the wordplay.
'tolkien monster' becomes 'orc' (orcs are creatures in The Lord of the Rings).
'concealed' becomes 'hid' ('hide' can be a synonym of 'conceal').
'orc'+'hid'='ORCHID'
(Other definitions for orchid that I've seen before include "Ornate flower" , "Flowering plant with bee and lady varieties" , "Family of flowers with unusual shapes and beautiful colours" , "lady's slipper, perhaps" , "Tropical flowering plant" .)