Flower, monster, placed under picture (10)
I believe the answer is:
snapdragon
'flower' is the definition.
(I know that snapdragon is a type of flower)
'monster placed under picture' is the wordplay.
'monster' becomes 'dragon' (dragon is a kind of monster).
'placed under' says to put letters next to each other.
'picture' becomes 'snap' (I've seen this before).
'dragon' after 'snap' is 'SNAPDRAGON'.
(Other definitions for snapdragon that I've seen before include "Kind of antirrhinum" , "One blooming" , "one's found in the garden" , "Perhaps Christmas entertainment" , "one found in bed" .)