As successor to a stern monarch (5)

I believe the answer is:

after

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

'as successor' is the definition.
I can't judge whether this definition defines the answer.

'stern monarch' is the wordplay.
'stern' becomes 'aft' (similar in meaning).
'monarch' becomes 'er' (abbreviation for Elizabeth Regina, British Queen).
'aft'+'er'='AFTER'

'to a' acts as a link.

Can you help me to learn more?

(Other definitions for after that I've seen before include "Following - behind" , "Subsequently" , "In honour of" , "Coming later in time" , "Following, consequent to" .)

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.