Old boss purchasing new plant (8)
I believe the answer is:
oleander
'plant' is the definition.
The answer is an example.
'old boss purchasing new' is the wordplay.
'old' becomes 'o' (abbreviation).
'boss' becomes 'leader' (I've seen this in another clue).
'purchasing' is an insertion indicator (some letters take possession of others).
'new' becomes 'n' (abbreviation as in New Testament NT).
'leader' placed around 'n' is 'leander'.
'o'+'leander'='OLEANDER'
(Other definitions for oleander that I've seen before include "Flowering plant" , "Reloaned for evergreen shrub with bright flowers" , "No dealer in evergreen shrub" , "poisonous plant" , "Red alone (anag.)" .)