Shrub Conservative woman planted across lake (8)
I believe the answer is:
camellia
'shrub' is the definition.
(I know this)
'conservative woman planted across lake' is the wordplay.
'conservative' becomes 'C' (UK political abbreviation).
'woman' becomes 'amelia' (woman's name).
'planted across' is an insertion indicator (some letters go around or across others).
'lake' becomes 'L' (geographical abbreviation).
'amelia' placed around 'l' is 'amellia'.
'c'+'amellia'='CAMELLIA'
(Other definitions for camellia that I've seen before include "Showy evergreen shrub" , "Shrub related to tea plant" , "Shrub with showy flowers" , "Japonica" , "Showy shrub, rel. to tea" .)