Truth and openness initially is displayed by every Irish prime minister (9)
I believe the answer is:
taoiseach
'prime minister' is the definition.
(I've seen this before)
'truth and openness initially is displayed by every' is the wordplay.
'initially' indicates taking the first letters.
'displayed by' says to put letters next to each other.
'every' becomes 'each' ('each' can be a synonym of 'every').
The first letters of 'truth and openness' is 'tao'.
'tao'+'is'+'each'='TAOISEACH'
'irish' acts as a link.
I am not very happy about this link. It may be part of another bit of the clue.
(Other definitions for taoiseach that I've seen before include "Irish PM" , "PM in Dublin" , "Irish head of government" , "Western PM" , "I 'ate chaos (anag) - Irish Republic's prime minister" .)