Break the law on the fourth of July? That's rich! (7)
I believe the answer is:
wealthy
'rich' is the definition.
(similar in meaning)
'break the law on the fourth of july?' is the wordplay.
'break' is an anagram indicator.
'on' says to put letters next to each other.
'the fourth of july?' becomes 'y' (4th letter of 'july').
'the'+'law'='thelaw'
'thelaw' with letters rearranged gives 'wealth'.
'wealth'+'y'='WEALTHY'
'that's' is the link.
(Other definitions for wealthy that I've seen before include "Rich and prosperous" , "Affluent" .)