Become angry about Republican surge (6)
I believe the answer is:
stream
'surge' is the definition.
(thesaurus)
'become angry about republican' is the wordplay.
'become angry' becomes 'steam'.
'about' indicates putting letters inside.
'republican' becomes 'r' (abbreviation).
'steam' placed around 'r' is 'STREAM'.
(Other definitions for stream that I've seen before include "Flow of water on land" , "Flow from master" , "Small narrow river" , "Moving water" , "Torrent" .)