Many a lie having been found out, is antagonistic (7)

I believe the answer is:

hostile

I'm a little stuck... Click here to teach me more about this clue!

'antagonistic' is the definition.
(similar in meaning)

'many a lie' is the wordplay.
'many' becomes 'host' (I've seen this before).
'a lie' becomes 'ile' (I can't justify this - if you can you should give a lot more credence to this answer).
'host'+'ile'='HOSTILE'

'having been found out is' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.

Can you help me to learn more?

(Other definitions for hostile that I've seen before include "Unkind" , "Bellicose" , "Enemy" , "Aggressive" , "Showing angry opposition" .)

I've seen this clue in the Evening Standard.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.