The term 'SANDWICH SUBMARINE' is a combination of two words, 'SANDWICH' and 'SUBMARINE'. A SANDWICH is a type of food consisting of two slices of bread with a filling in between, while a SUBMARINE is a type of vessel that can travel underwater. The crossword solution for this term is HERO, which is a four-letter word. A HERO is someone who is admired for their courage, outstanding achievements, or noble qualities. Therefore, the term 'SANDWICH SUBMARINE' can be interpreted as someone who is brave and heroic enough to take on a difficult task, such as travelling underwater in a SUBMARINE to deliver a SANDWICH.