Plan to welcome His Excellency at last (2,3,3)
I believe the answer is:
in the end
'at last' is the definition.
('in the end' can be a synonym of 'at last')
'plan to welcome his excellency' is the wordplay.
'plan' becomes 'intend' (intending is a kind of planning).
'to welcome' indicates putting letters inside (in sense of 'inviting in').
'his excellency' becomes 'he'.
'intend' placed around 'he' is 'IN THE END'.
(Other definitions for in the end that I've seen before include "At long last" , "Finally" , "Eventually" , "Then Enid came at last" , "Ultimately" .)