Crossword Genius

After preliminary introduction to ecdysiasts, party got livelier (6,2)

Ross

I believe the answer is:

heated up

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

'got livelier' is the definition.
I can't tell whether this definition defines the answer.

'after preliminary introduction to ecdysiasts party' is the wordplay.
'after preliminary' becomes 'heat' (I can't justify this - if you can you should give a lot more credence to this answer).
'introduction to' suggests taking the first letters.
'party' becomes 'dup' (Democratic Unionist Party).
The first letter of 'ecdysiasts' is 'e'.
'heat'+'e'+'dup'='HEATED UP'

Can you help me to learn more?

I've seen this clue in The Independent.
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.