Mum runs drug shop in America (6)
I believe the answer is:
market
'shop in america' is the definition.
'market' can be an answer for 'shop' (thesaurus). I'm not sure about the 'in america' bit.
'mum runs drug' is the wordplay.
'mum' becomes 'ma' (ma can mean mother).
'runs' becomes 'r' (cricket abbreviation).
'drug' becomes 'ket' (I can't explain this - if you can you should believe this answer much more).
'ma'+'r'+'ket'='MARKET'
Can you help me to learn more?
(Other definitions for market that I've seen before include "Advertise, promote" , "Trading area" , "Try to sell" , "(Place of) buying and selling" , "bargain" .)