Cheer queen, also in the flowering shrub (8)
I believe the answer is:
oleander
'flowering shrub' is the definition.
(I've seen this before)
'cheer queen also in' is the wordplay.
'cheer' becomes 'ole' (I have seen 'Spanish cheer ' mean 'ole' so perhaps 'cheer' could also mean 'ole').
'queen' becomes 'ER' (abbreviation for Elizabeth Regina).
'also' becomes 'and' (I've seen this before).
'in' means one lot of letters goes inside another.
'ole'+'er'='oleer'
'oleer' going around 'and' is 'OLEANDER'.
'the' acts as a link.
(Other definitions for oleander that I've seen before include "Evergreen flowering shrub from olden era" , "poisonous plant" , "Reloaned for evergreen shrub with bright flowers" , "Flowering shrub from olden era, oddly" , "Poisonous shrub, also called rosebay" .)