### Clue: Frank Sinatra's heart broken, nation supporting Martin initially (3-2-3)
### Answer: MAN-TO-MAN 
 ### Explanation: Frank Sinatra's heart broken, nation supporting Martin initially (3-2-3)
*(nat) (the heart of "Si**NAT**ra") + **OMAN **("nation") "supporting" **M**(artin), so **M****(ANT)OMAN