Miser upset about landlord’s political belief in the US (13)
I believe the answer is:
republicanism
'political belief in the us' is the definition.
(ideology of the Republican party)
'miser upset about landlord's' is the wordplay.
'upset' indicates anagramming the letters.
'about' means one lot of letters goes inside another.
'landlord' becomes 'publican' (I've seen this before).
'miser' anagrammed gives 'reism'.
'reism' placed around 'publican' is 'REPUBLICANISM'.
(Other definitions for republicanism that I've seen before include "One of main US political movements" , "Policy of one US party" , "Belief that monarchies should be abolished" .)