PM is to broadcast about introduction of allowances per person (9)
I believe the answer is:
taoiseach
'pm' is the definition.
(I've seen this before)
'is to broadcast about introduction of allowances per person' is the wordplay.
'broadcast' indicates anagramming the letters (letters scattered or cast around).
'about' indicates putting letters inside.
'introduction of' suggests taking the first letters.
'per person' becomes 'each' (eg 'one each' means 'one per person').
The first letter of 'allowances' is 'a'.
'is'+'to'='isto'
'isto' with letters rearranged gives 'tois'.
'tois' placed around 'a' is 'taois'.
'taois'+'each'='TAOISEACH'
(Other definitions for taoiseach that I've seen before include "Irish head of government" , "Irish PM" , "Irish premier" , "PM in Dublin" , "Leader of the government" .)