Alternatively, a politician's public speaking (7)
I believe the answer is:
oratory
'public speaking' is the definition.
(I've seen this before)
'alternatively a politician's' is the wordplay.
'alternatively' becomes 'or'.
'politician' becomes 'tory' (I've seen this before).
'or'+'a'+'tory'='ORATORY'
(Other definitions for oratory that I've seen before include "Small chapel for private worship" , "church" , "Cicero's art" , "Art or skill of public speaking" , "Place for private prayer" .)