PM a cheat, so I gathered (9)
I believe the answer is:
taoiseach
'pm' is the definition.
(I've seen this before)
'a cheat so i gathered' is the wordplay.
'gathered' is an anagram indicator (the letters are gathered into a new order).
'a'+'cheat'+'so'+'i'='acheatsoi'
'acheatsoi' with letters rearranged gives 'TAOISEACH'.
(Other definitions for taoiseach that I've seen before include "Irish head of government" , "Leader of the government" , "Western PM" , "PM in Dublin" , "Irish PM" .)