Sandwich possibly good, certainly with large filling (4,6)
I believe the answer is:
golf course
'sandwich possibly' is the definition.
(Sandwich is home to two golf courses)
'good certainly with large filling' is the wordplay.
'good' becomes 'g' (abbreviation).
'certainly' becomes 'ofcourse' (both can be used to answer in the affirmative).
'with' is a charade indicator (letters next to each other).
'large' becomes 'L' (eg in clothes sizes).
'filling' is an insertion indicator.
'g'+'ofcourse'='gofcourse'
'gofcourse' enclosing 'l' is 'GOLF-COURSE'.
(Other definitions for golf course that I've seen before include "Royal Troon or Carnoustie, for example" , "area for drivers" , "Possibly links" .)