If the clutch was just done (20 miles or less) there is a chance penetration spray is burning off. If it has been longer than ~20 miles then there may be a leak somewhere, none related to the clutch job. Assuming the car has over 20 miles then I would be proactive with sorting it out, before it has a chance to possibly damage the motor.
Radiator Pressure Testing equipment should be able to find a coolant leak
White smoke could also be an oil leak, often common after an oil change since oil can get on the exhaust manifold heat shields.
Let us know what you end up finding.