Regrettably went back to the motorway for some sausage (6)
I believe the answer is:
salami
'some sausage' is the definition.
(salami is a kind of sausage)
'regrettably went back to the motorway' is the wordplay.
'regrettably' becomes 'alas' (I've seen this before).
'went back' is a reversal indicator.
'to the motorway' becomes 'mi' (resembles M1, English motorway).
'alas' in reverse letter order is 'sala'.
'sala'+'mi'='SALAMI'
'for' acts as a link.
(Other definitions for salami that I've seen before include "Spicy preserved sausage" , "Highly-seasonal sausage" , "A highly seasoned type of sausage" , "Highly spiced sausage" , "Savoury snack" .)