To tolerate hosting rightwing brother, or leave him on his own? (6)
I believe the answer is:
strand
'brother or leave him on his own?' is the definition.
Although both the answer and definition are singular nouns, I don't see how one could define the other.
'to tolerate hosting rightwing' is the wordplay.
'to tolerate' becomes 'stand' ('stand' can be a synonym of 'tolerate').
'hosting' is an insertion indicator (inserted letters are welcomed in or hosted).
'rightwing' becomes 'r' (this could be a standard abbreviation of which I'm unaware).
'stand' enclosing 'r' is 'STRAND'.
Can you help me to learn more?
(Other definitions for strand that I've seen before include "Thread - London street" , "string" , "Beach; London road" , "sometimes washed by the sea" , "Maroon - thread" .)