Guardian article used in court worried Republican (7)
I believe the answer is:
curator
'guardian' is the definition.
(curator is a kind of guardian)
'article used in court worried republican' is the wordplay.
'article' becomes 'a' (indefinite article).
'used in' means one lot of letters goes inside another.
'worried' indicates anagramming the letters.
'republican' becomes 'r' (abbreviation).
'court' anagrammed gives 'curto'.
'a' placed inside 'curto' is 'curato'.
'curato'+'r'='CURATOR'
(Other definitions for curator that I've seen before include "Cultural employee" , "museum boss" , "man in the museum?" , "Museum custodian" , "Person in charge of a museum" .)