The most common and most likely answer to this crossword clue is the 6 letter word ONSIDE
I've seen this crossword clue in The Times
O
N
S
I
D
E
More clues leading to the result ONSIDE
- I must keep small boy towing the line
- Edison with eccentric characters working for same goal
- Part of revolution’s ideology considered legitimate?
- Where fielders may be in a position to play
- Team following forward, working towards the same goal
- Seaman catches new fish in position where netting’s permitted
- Supporting position of legal hooker?
- Half the field in one sport, legal in another?
- In the team, on the wing, not breaking the rules
- Correctly positioned for the pull shot?
Buddy explains!

The straight part
We know that "towing the line" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case towing the line = onside.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 ONSIDE mean?
ONSIDE noun- The portion of the playing area where one can legally play the ball, puck, etc.
- The side of a vehicle on which the driver primarily propels it.
- Not in an offside position; In the part of the playing area where one can legally play the ball, puck, etc.
- On the side of a vehicle from which the driver, paddler, etc. propels it.
- Favourably located, from the point of view of the player taking a finesse.
- In agreement or support; on board.