Some members emphasise menace, bringing up vengeful rival (7)
I believe the answer is:
nemesis
'vengeful rival' is the definition.
'nemesis' can be an answer for 'rival' (I have seen 'Unbeatable rival ' mean 'nemesis' so perhaps 'rival' could also mean 'nemesis'). I am unsure of the 'vengeful' bit.
'some members emphasise menace bringing up' is the wordplay.
'some' indicates the answer is hidden within the clue (some parts of the word are used).
'bringing up' says the letters should be written in reverse (I've seen 'brought up' mean this (in a down clue, letters go up)).
'sisemen' is hidden in the letters of 'members emphasise menace'.
'sisemen' reversed gives 'NEMESIS'.
Can you help me to learn more?
(Other definitions for nemesis that I've seen before include "causes downfall" , "E'en miss (anag.)" , "Destiny" , "Unbeatable rival" , "Goddess of revenge - seems in (anag)" .)