Refuge of PM once, saving face (4)
I believe the answer is:
lair
'refuge' is the definition.
(I've seen this in another clue)
'pm once saving face' is the wordplay.
'pm once' becomes 'Blair' (Tony Blair).
'saving face' means to remove the first letter (removing or saving the \'face\' of the word).
'blair' with its first letter taken away is 'LAIR'.
'of' acts as a link.
(Other definitions for lair that I've seen before include "animal refuge" , "Place of seclusion (informal)" , "Hiding place, den" , "beastly retreat" , "Home of a beast" .)