Sandwich with a brown filling? That's very obvious (7)
I believe the answer is:
blatant
'that's very obvious' is the definition.
(I've seen this before)
'sandwich with a brown' is the wordplay.
'sandwich' becomes 'blt' (BLT is an example).
'with' means one lot of letters goes inside another.
'brown' becomes 'tan' (tan is a kind of brown).
'a'+'tan'='atan'
'blt' enclosing 'atan' is 'BLATANT'.
'filling?' is the link.
This may not be right. It may be part of another bit of the clue.
(Other definitions for blatant that I've seen before include "Very noticeable and obtrusive" , "Very obvious and without shame" , "Open, unashamed" , "Unashamed, flagrant" , "Brazen, flagrant" .)