Some sexy group needing erection (4)
I believe the answer is:
orgy
This clue might be a double definition.
'some sexy group' is the first definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'erection' is the second definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps they are linked in a way I don't understand?
'needing' is the link.
Can you help me to learn more?
(Other definitions for orgy that I've seen before include "Bacchanal" , "debauched scene" , "riot" , "Wild overindulgent party" , "Rumpy-pumpy party" .)