The most common and most likely answer to this crossword clue is the 8 letter word LINESMAN
I've seen this crossword clue in The Daily Telegraph
L
I
N
E
S
M
A
N
More clues leading to the result LINESMAN
- Assistant ref’s backing nothing — means one needs to replace
- Official verses and unfinished scores
- Sports official ordered inn meals
- Flag-waver's verses and unfinished scores
- Sports official is a poet, as it were
- Official who’s often up the pole?
- Recalling duck names confused park official
- Person making judgment in court leading to outcry, so to speak?
- Referee means to change after no score upset
- One who calls out at court
Buddy explains!

The straight part
We know that "Referee" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case referee = linesman.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 LINESMAN mean?
LINESMAN noun- An assistant referee.
- A male line judge.
- An official whose primary task is to watch the blue line and determine when there has been an offside.
- An official whose primary task is to determine whether there has been a line of scrimmage violation.
- A person employed to work on electrical lines; a lineman.
- A private in the line.