Patron Saint oppressed by a menace abroad (8)
I believe the answer is:
maecenas
'patron' is the definition.
(patron of several Roman poets)
'oppressed by a menace abroad' is the wordplay.
'oppressed' becomes 'as' (I am not sure about this - if you are sure you should believe this answer much more).
'by' says to put letters next to each other.
'abroad' indicates an anagram.
'menace' is an anagram of 'maecen'.
'as' put after 'maecen' is 'MAECENAS'.
'saint' acts as a link.
This may not be right. It may belong to another bit of the clue.
(Other definitions for maecenas that I've seen before include "Generous patron of the arts" , "Rich patron" , "Roman patron" .)