Can't he add right? (3)

I believe the answer is:

dad

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

'can't he' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.

'add right?' is the wordplay.
'add' can be anagrammed to 'DAD'.
But, I'm not clear how this is indicated.

Can you help me to learn more?

(Other definitions for dad that I've seen before include "Mum's mate" , "Popular and informal father" , "Pa" , "Papa" , "Father, in short" .)

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.