Sarcastic press mimic A-list insiders (8)
I believe the answer is:
ironical
'sarcastic' is the definition.
(similar in meaning)
'press mimic a-list insiders' is the wordplay.
'press' becomes 'iron' (ironing is a kind of pressing).
'mimic a-list insiders' becomes 'ical' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'iron'+'ical'='IRONICAL'
Can you help me to learn more?
(Other definitions for ironical that I've seen before include "skittish" , "With humorously opposite meaning" , "Sarcastic, using words with inverted meaning" , "Perversely humorous" , "Socratic method of discussion, professing ignorance" .)