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 can't justify this - if you can you should give a lot more credence to this answer).
'after' means one lot of letters go next to another.
'pharmacist' becomes 'chemist' (synonyms).
'shortened' means to remove the last letter.
'chemist' with its last letter taken off is 'chemis'.
'e' put 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" .)