Seize her in the auditorium, Groucho! (6)
I believe the answer is:
julius
'the auditorium groucho' is the definition.
I can't tell whether this defines the answer.
'seize her' is the wordplay.
I cannot quite understand how this works, but
'her' could be 'juli' and 'juli' is present in the answer.
The remaining letters 'us' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'in' acts as a link.
Can you help me to learn more?
(Other definitions for julius that I've seen before include "Gaius - Caesar" , "Play set in ancient Rome" , "Shakespeare play" , "Shak. Roman play" , "The Caesar stabbed by Brutus" .)