The most common and most likely answer to this crossword clue is the 8 letter word TOASTIES
I've seen this crossword clue in The Daily Telegraph
T
O
A
S
T
I
E
S
Buddy explains!

The straight part
We know that "Sandwiches" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sandwiches = toasties.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
Crossword Answer definitions
TOASTIES noun- Toasted sandwich, a jaffle