U2 member hugs old boy and promiscuous primate! (6)
I believe the answer is:
bonobo
'promiscuous primate' is the definition.
'bonobo' can be an answer for 'primate' (bonobo is a kind of primate). I am unsure of the 'promiscuous' bit.
'u2 member hugs old boy' is the wordplay.
'uo member' becomes 'bono' (I am not sure about this - if you are sure you should believe this answer much more).
'hugs' means one lot of letters goes inside another.
'old boy' becomes 'OB' (abbreviation for a private school 'old boy').
'bono' placed around 'ob' is 'BONOBO'.
'and' acts as a link.
Can you help me to learn more?
(Other definitions for bonobo that I've seen before include "our nearest relative" , "Small chimpanzee" .)