Somewhat controversial treasure (5)
I believe the answer is:
trove
'treasure' is the definition.
(trove is a kind of treasure)
'somewhat controversial' is the wordplay.
'somewhat' says the answer is hidden in the clue.
'TROVE' can be found hidden inside 'controversial'.
(Other definitions for trove that I've seen before include "Collection of treasures" , "Store of valuable things" , "Valuable collection" , "Treasure stash" , "Hidden treasure for voter" .)