More vigorous yet hollow greeting to the monarch (7)

I believe the answer is:

pithier

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

'more vigorous yet' is the definition.
I can't tell whether this defines the answer.

'hollow greeting to the monarch' is the wordplay.
'hollow' becomes 'pit' (pit is a kind of hollow).
'greeting' becomes 'hi' (hi is a kind of greeting).
'to the monarch' becomes 'ER' (abbreviation for Elizabeth Regina, British Queen).
'pit'+'hi'+'er'='PITHIER'

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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.