The origin of a pop group (7)
I believe the answer is:
genesis
This clue could be a double definition.
'the origin' is the first definition.
('genesis' can be a synonym of 'origin')
'pop group' is the second definition.
'genesis' can be an answer for 'group' (rock band). I am not certain of the 'pop' bit.
'of a' acts as a link.
Can you help me to learn more?
(Other definitions for genesis that I've seen before include "Beginning (in the Bible)" , "Origin (of the Old Testament?)" , "OT opening" , "First book of the Old Testament" , "name of group" .)