Great excitement alarms a group - holding it back (6)
I believe the answer is:
orgasm
'great excitement' is the definition.
'orgasm' can be an answer for 'excitement' (I have seen 'Immoderate excitement' mean 'orgasm' so perhaps 'excitement' could also mean 'orgasm'). I'm unsure of the 'great' bit.
'alarms a group holding it back' is the wordplay.
'ORGASM' is hidden backwards within the letters.
However, I'm uncertain how this is indicated.
Can you help me to learn more?
(Other definitions for orgasm that I've seen before include "Fit of intense excitement" , "Bout of intense excitement" , "Practising conjugation may achieve it" , "Immoderate excitement" .)