Cue after grabbing a rest (9)

I believe the answer is:

remainder

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

'rest' is the definition.
(synonyms)

'cue after grabbing a' is the wordplay.
'cue' becomes 'remind' (synonyms).
'after' becomes 'er' (I can't explain this - if you can you should believe this answer much more).
'grabbing' means one lot of letters goes inside another.
'remind'+'er'='reminder'
'reminder' going around 'a' is 'REMAINDER'.

Can you help me to learn more?

(Other definitions for remainder that I've seen before include "book going cheap" , "Surplus" , "Rest - sell off (books) cheap" , "Balance" , "that's left" .)

I've seen this clue in The Times.

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.