Brilliant tirade about foreign aid (7)
I believe the answer is:
radiant
'brilliant' is the definition.
(I've seen this before)
'tirade about foreign aid' is the wordplay.
'tirade' becomes 'rant' (both can mean an angry outburst).
'about' is an insertion indicator.
'foreign' indicates anagramming the letters (foreign order of the letters).
'aid' is an anagram of 'dia'.
'rant' enclosing 'dia' is 'RADIANT'.
(Other definitions for radiant that I've seen before include "Resplendent" , "Incandescent" , "Shining brightly, being at nadir" , "Lit up" , "Beautiful" .)