Antics involved gagging angry niche experts (11)
I believe the answer is:
technicians
'experts' is the definition.
(technician is a kind of expert)
'antics involved gagging angry niche' is the wordplay.
I cannot really see how this works, but
an anagram of 'niche' is 'echni' which is present in the answer.
an anagram of 'antics' is 'tcians' which is within the left over letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Another definition for technicians that I've seen is " Laboratory workers".)