Identify the subject and predicate in the sentence
Please ask Mr. Clarkson to meet me in the hall.

Dear Student, 

The sentence : Please ask Mr. Clarkson to meet me in the hall. 
It actually means : (You) Please ask Mr. Clarkson to meet me in the hall.
​​​​​Subject - You (​​Here, the subject is implied and not stated explicitly).
Predicate - Please ask Mr. Clarkson to meet me in the hall.

Regards,