Drug supplied after pharmacist shortened dress (7)
I believe the answer is:
chemise
'dress' is the definition.
(type of dress)
'drug supplied after pharmacist shortened' is the wordplay.
'drug supplied' becomes 'e' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'after' is a charade indicator (letters next to each other).
'pharmacist' becomes 'chemist' (synonyms).
'shortened' means to remove the last letter.
'chemist' with its last letter removed is 'chemis'.
'e' after 'chemis' is 'CHEMISE'.
Can you help me to learn more?
(Other definitions for chemise that I've seen before include "Apron" , "Loose-fitting dress without a waist" , "garment" , "Shift" , "Loose-fitting shirtlike dress" .)