Example:
A ugly rumor about him circulated in the city. The person who started it was nothing more, nothing less than his wife.
Can I use the phrase in this way? If not, what's a more adequate option?
Example:
A ugly rumor about him circulated in the city. The person who started it was nothing more, nothing less than his wife.
Can I use the phrase in this way? If not, what's a more adequate option?
You can use the phrase "nothing more, nothing less" in relation to a person, just not as you have. As @CowperKettle has said, the phrase you are looking for is "none other than" (from Oxford Dictionaries):
none other than
Phrase
Used to emphasize the surprising identity of a person or thing:
"her first customer was none other than Henry du Pont"
You might use "nothing more, nothing less" in relation to a person who thinks they are of higher status than they actually are, or a person who tries to act outside their remit or area of responsibility. For example:
He spoke back to the Sergeant. He had to remember he was a private: nothing more, nothing less.