Troll taking no medication's hiding (5)
I believe the answer is:
gnome
'troll' is the definition.
(I've seen this in another clue)
'taking no medication's hiding' is the wordplay.
'hiding' says the answer is hidden in the clue.
'GNOME' is hidden within 'taking no medications'.
(Other definitions for gnome that I've seen before include "Swiss banker" , "little chap fishing in the garden" , "Small fellow" , "Maxim" , "Mythical creature" .)