The most common and most likely answer to this crossword clue is the 6 plus 3 letter word AEGEAN SEA
A
E
G
E
A
N
S
E
A
More clues leading to the result AEGEAN SEA
- Aeneas’ age? It’s uncertain, but the location is somewhere around Greece
- Roads sound here mainly
- Main energy supplied by electrical company once going to Welsh city
- What held up Greek fleet en route to Troy?
- Mainly it separates Greece from Turkey
- Sing first and last note in C to evoke Mediterranean waters
- Gee, Ana breaks sticker almost between Greece and Turkey
- Aeneas' age? It's uncertain, but the location is somewhere around Greece
Buddy explains!

The straight part
We know that "Main" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case main = aegean sea.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.