A hundred and two sailors share the bill (2-4)
I believe the answer is:
co-star
'share the bill' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'a hundred and two sailors' is the wordplay.
'two sailors' can mean two substitutions for 'sailor'.
'a hundred' becomes 'C' (Roman numeral).
'and' says to put letters next to each other.
'sailor' becomes 'os' (ordinary seaman).
'sailor' becomes 'tar' (slang term for a sailor).
'c'+'os'+'tar'='CO-STAR'
Can you help me to learn more?
(Other definitions for co-star that I've seen before include "Performer meriting joint billing" , "Actor sharing top billing" , "Joint main actor" , "Be joint lead (in film, play, etc)" , "Performer of equal importance" .)