Tablet or your first public punishment (7)
I believe the answer is:
pillory
'public punishment' is the definition.
Although both the answer and definition are singular nouns, I can't understand how they can define each other.
'tablet or your first' is the wordplay.
'tablet' becomes 'pill' (synonyms).
'your first' becomes 'y' (1st letter of 'your').
'pill'+'or'+'y'='PILLORY'
Can you help me to learn more?
(Other definitions for pillory that I've seen before include "Expose to public ridicule" , "place of punishment" , "Expose to public derision" , "Assail; old punishment frame" , "Publicly ridicule" .)