The ones on the fourth of July (4)
I believe the answer is:
they
'the ones' is the definition.
Both the answer and definition are plural nouns.
Perhaps you can see an association between them that I can't see?
'on the fourth of july' is the wordplay.
'on' says to put letters next to each other.
'fourth of july' becomes 'y' (4th letter of 'july').
'the'+'y' is 'THEY'.
Can you help me to learn more?
(Other definitions for they that I've seen before include "People in general" , "Do -- Know It's Christmas (Band Aid)" , "Those people (vb. subject)" , "Pronoun for people" , "Third person plural" .)