Look disapprovingly at quarrel between foreign extremists (5)
I believe the answer is:
frown
'look disapprovingly' is the definition.
'frown' can be an answer for 'look' (I have seen 'Dirty look ' mean 'frown' so perhaps 'look' could also mean 'frown'). I am not certain of the 'disapprovingly' bit.
'quarrel between foreign extremists' is the wordplay.
'quarrel' becomes 'row' (synonyms).
'between' is an insertion indicator.
'extremists' means to remove the middle letters (letters on the extreme ends of the word).
'foreign' with its centre taken out is 'fn'.
'row' going inside 'fn' is 'FROWN'.
'at' is the link.
Can you help me to learn more?
(Other definitions for frown that I've seen before include "make headlines?" , "Wrinkle brow" , "Knit one's brows" , "Disapproving look" , "Indicate disapproval" .)