Plant that may destroy a toilet? (8)
I believe the answer is:
lavender
'plant that may destroy a' is the definition.
The answer and definition can be both plants as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'toilet?' is the wordplay.
I cannot really understand how this works, but
'toilet?' could be 'lav' ('lav' can be a synonym of 'toilet') and 'lav' is found in the answer.
This explanation may well be incorrect...
(Other definitions for lavender that I've seen before include "Plant used in perfumery" , "bloomer" , "Plant prized for its scent" , "Fragrant purple flower used to scent linen etc" , "Shrub with fragrant purple flowers, used to scent linen" .)