Angry expression results in fight that splits extremist faction (5)
I believe the answer is:
frown
'angry expression' is the definition.
'frown' can be an answer for 'expression' (I have seen 'gloomy expression' mean 'frown' so perhaps 'expression' could also mean 'frown'). I'm not certain of the 'angry' bit.
'fight that splits extremist faction' is the wordplay.
'fight' becomes 'row' (I've seen this in another clue).
'that splits' indicates putting letters inside (inserted letters split open the word).
'extremist' suggests removing the centre (I've seen 'extremists' mean this).
'faction' with its centre removed is 'fn'.
'row' inserted within 'fn' is 'FROWN'.
'results in' is the link.
Can you help me to learn more?
(Other definitions for frown that I've seen before include "Indicate disapproval" , "Look displeased" , "Scowl, look crossly" , "Glower" , "gloomy expression" .)