... hooking up and having sex (8)
I believe the answer is:
coupling
'sex' is the definition.
(coupling is a kind of sex)
'hooking up and' is the wordplay.
I cannot really understand how this works, but
'up' is within the answer.
'and' could be 'n' (common abbreviation for 'and') and 'n' is located in the answer.
This explanation may well be incorrect...
'having' is the link.
Can you help me to learn more?
(Other definitions for coupling that I've seen before include "Joining device" , "Mechanical device" .)