The most common and most likely answer to this crossword clue is the 4 plus 4 letter word GOAL LINE
G
O
A
L
L
I
N
E
More clues leading to the result GOAL LINE
- Bet everything Spain makes a mark in football
- Side on pitch try, tired at end of game
- Exhausted after try, back in glee making mark on the field
- A kind of technology used to protect everyone on island
- Galileo worked outside new boundary
- Mark at Old Trafford completely exhausted, having little energy after game
Buddy explains!

The straight part
We know that "boundary" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case boundary = goal line.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.