Gruesome plant? (3)
I believe the answer is:
rue
'plant?' is the definition.
(type of shrub)
'gruesome' is the wordplay.
'RUE' is hidden in amongst the letters.
However, I'm uncertain how the hidden word is indicated.
Can you help me to learn more?
(Other definitions for rue that I've seen before include "show you're sorry!" , "Fish eggs" , "Deplore" , "Feel bad" , "Bitterly regret - plant" .)