A suitable one, salesman sent over drink before meal (8)
I believe the answer is:
aperitif
'drink before meal' is the definition.
(I've seen this before)
'a suitable one salesman sent over' is the wordplay.
'suitable' becomes 'fit' ('fit' can be similar in meaning to 'suitable').
'one' becomes 'i' (Roman numeral).
'salesman' becomes 'rep' (I've seen this before).
'sent over' shows that the letters should be reversed in order.
'fit'+'i'+'rep'='fitirep'
'fitirep' backwards is 'peritif'.
'a'+'peritif'='APERITIF'
(Other definitions for aperitif that I've seen before include "Pre-meal drink" , "Preprandial drink" , "wine, possibly, before meal" , "Pre-dinner drink" , "What's drunk before a meal?" .)