Lout smashed alien market (6)
I believe the answer is:
outlet
'market' is the definition.
(I've seen this before)
'lout smashed alien' is the wordplay.
'smashed' indicates an anagram.
'alien' becomes 'et' (extra terrestrial).
'lout' with letters rearranged gives 'outl'.
'outl'+'et'='OUTLET'
(Other definitions for outlet that I've seen before include "Vent for water or feelings" , "Shop (retail)" , "Exit pipe" , "River mouth; socket" , "River mouth; shop" .)