Hero-worshipper behind Obama, initially, or Bush (8)
I believe the answer is:
oleander
'bush' is the definition.
(oleander is a type of bush)
'hero-worshipper behind obama initially' is the wordplay.
'hero-worshipper' becomes 'leander' (I've seen this before).
'behind' is a charade indicator (letters next to each other).
'initially' indicates taking the first letters.
The initial letter of 'obama' is 'o'.
'leander' after 'o' is 'OLEANDER'.
'or' is the link.
(Other definitions for oleander that I've seen before include "poisonous plant" , "Poisonous shrub, also called rosebay" , "No leader, oddly, for the flowering shrub" , "Reloaned for evergreen shrub with bright flowers" , "'Adorn eel, badly, with this shrub (8)'" .)