Try to notice the neck and joint of the clutch if it's leaking then it's time to change the clutch
The radiator if choked and serviced will only bring back the problem at a later time it's much better to toss in a new high volume radiator even if the radiator is not choked if you see it's plastic body turning in to a shade of brown or if aluminum fins oxidation then it's high time you get that radiator out of the equation
When changing the radiator it's always better to toss the thermostat with it as it too has worn-out
(Only recommend for garage)
While the car is running touch the upper and lower hose if the thermostat is bad there will be drastic difference in temperature of both pipes
And open the radiator cap and notice the water at the cap if it's turning nicely at the cap place then the water pump is working strong
Notice the leaks and air in system
These steps mentioned above is for professionals only and should be executed by a professional workshop technicians under no circumstances us should be held responsible as these steps could and can inflict life altering harm