Crossword Genius

Rig on a device must stop short of blockhead (9)

Ross

I believe the answer is:

ignoramus

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

'rig' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.

'device must stop short of blockhead' is the wordplay.
I cannot really understand how this works, but
'device' could be 'ram' (RAM is an example) and 'ram' is found within the answer.
'of' could be 'o' and 'o' is located in the answer.
This explanation may well be incorrect...

'on a' acts as a link.

Can you help me to learn more?

(Other definitions for ignoramus that I've seen before include "I wouldn't know" , "One could be blissful it's said" , "Uneducated person" , "Idiot" , "Dimwit" .)

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.