Beers mother gets in tin for trader (8)
I believe the answer is:
salesman
'for trader' is the definition.
(thesaurus)
'beers mother gets in tin' is the wordplay.
'beers' becomes 'ales' (I've seen this before).
'mother' becomes 'ma' (Ma is another word for mother or mum).
'gets in' indicates putting letters inside.
'tin' becomes 'Sn' (Sn is the chemical symbol for tin).
'ales'+'ma'='alesma'
'alesma' put into 'sn' is 'SALESMAN'.
(Other definitions for salesman that I've seen before include "Death of a . . . . . . . . (Arthur Miller) (8)" , "Fermented honey drink" , "Slam Sean badly for his selling" , "One selling goods" , "He's a vendor" .)