Rose, upset about Nat being in politics (7)
I believe the answer is:
senator
'being in politics' is the definition.
'senator' can be an answer for 'being' (senator is a kind of being). I'm not certain of the 'in politics' bit.
'rose upset about nat' is the wordplay.
'upset' is an anagram indicator.
'about' indicates putting letters inside.
'rose' anagrammed gives 'seor'.
'seor' enclosing 'nat' is 'SENATOR'.
Can you help me to learn more?
(Other definitions for senator that I've seen before include "American politician" , "Member of Upper House engaged in treason" , "Member of government" , "Member of upper house of legislature" , "One from uni's governing body" .)