Irish premier, his ace reforms to follow universal principle (9)
I believe the answer is:
taoiseach
'irish premier' is the definition.
(I've seen this before)
'his ace reforms to follow universal principle' is the wordplay.
'reforms' indicates an anagram.
'to follow' says to put letters next to each other (some letters go after or follow others).
'universal principle' becomes 'tao' (Tao is an example. I am not sure about the 'universal' bit.).
'his'+'ace'='hisace'
'hisace' with letters rearranged gives 'iseach'.
'iseach' put after 'tao' is 'TAOISEACH'.
Can you help me to learn more?
(Other definitions for taoiseach that I've seen before include "Irish head of government" , "Leader of the government" , "Irish premier" , "Western PM" , "PM in Dublin" .)