The most common and most likely answer to this crossword clue is the 9 letter word TOUCHLINE
I've seen this crossword clue in The Daily Telegraph
T
O
U
C
H
L
I
N
E
More clues leading to the result TOUCHLINE
Buddy explains!
The straight part
We know that "side of playing area" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case side of playing area = touchline.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 TOUCHLINE mean?
TOUCHLINE noun- One of the lines that mark the border limits of the pitch.