The most common and most likely answer to this crossword clue is the 7 letter word SALIENT
I've seen this crossword clue in The Guardian
S
A
L
I
E
N
T
More clues leading to the result SALIENT
- Stranger occupies street, striking
- Way to capture foreign part of fortification
- Isn’t ale newly brewed outstanding?
- Most important way to welcome foreigner
- Important member of the great and good welcominga foreigner
- Conspicuous foreigner in street
- Prominent street captivates outsider
- Prominent foreigner seen in street
- A silent suspect, conspicuous
- Conspicuous way to involve stranger
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 = salient.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.
What does SALIENT mean?
SALIENT noun- An outwardly projecting part of a fortification, trench system, or line of defense.
- Worthy of note; pertinent or relevant.
- Prominent; conspicuous.
- (usually of a quadruped) Depicted in a leaping posture.
- Projecting outwards, pointing outwards.
- Moving by leaps or springs; jumping.
- Shooting or springing out; projecting.
- Denoting any angle less than two right angles.