For example, Ovid's number one (3)
I believe the answer is:
ego
'number one' is the definition.
(I've seen this before)
'for example ovid's' is the wordplay.
'for example' becomes 'e.g.' (short for 'exempli gratia', 'for example' in Latin).
'ovid's' becomes 'o' (this could be a standard abbreviation of which I'm unaware).
'eg'+'o'='EGO'
Can you help me to learn more?
(Other definitions for ego that I've seen before include "Aspect of the personality" , "number one" , "Self-esteem, sense of self" , "(Self-assertive) personality" , "Conscious self" .)