Leader of House gets installed in seat — what a relief! (4)
I believe the answer is:
phew
'what a relief' is the definition.
(I've seen this in other clues)
I cannot understand how the remainder of the clue works.
Can you help me to learn more?
(Other definitions for phew that I've seen before include "Good gracious, its hot!" , "Exclamation of relief" , "Recover unharmed" , "Gosh, that's a relief!" , "Sound relieved" .)