Would he cheat a motherless man? (3)
I believe the answer is:
don
'would he' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'cheat a motherless man?' is the wordplay.
'cheat' becomes 'do'.
'a motherless man?' becomes 'n' (knight, a man in chess. I am not sure about the 'motherless' bit.).
'do'+'n'='DON'
Can you help me to learn more?
(Other definitions for don that I've seen before include "A mafia chief or Spanish grandee" , "A Spanish grandee like Quixote" , "Spanish nobleman" , "University teacher" , "A mafia chief or Spanish lord" .)