I work out after tablet (3)
I believe the answer is:
ego
'i' is the definition.
('I' in Latin)
'work out after tablet' is the wordplay.
'work out' becomes 'go' (synonyms. I am not sure about the 'out' bit.).
'after' is a charade indicator (letters next to each other).
'tablet' becomes 'e' (E can mean ecstasy or an ecstasy tablet).
'go' after 'e' is 'EGO'.
Can you help me to learn more?
(Other definitions for ego that I've seen before include "See 21 Down" , "Self-esteem, conceit" , "One's image of oneself" , "Inner self" , "Personal pride" .)