Support for the Patriotic Front (4)
I believe the answer is:
prop
'support' is the definition.
(prop up can mean to support)
'for the patriotic front' is the wordplay.
'for' becomes 'pro' (as in being 'pro' or in favour of something).
'front' says to take the initial letters.
The first letter of 'patriotic' is 'p'.
'pro'+'p'='PROP'
(Other definitions for prop that I've seen before include "Stay" , "Support (a rugby player?)" , "Object used on the set of a play" , "Shore for 4 down" , "one playing Rugby" .)