20 down
Towards
the
back,
seat
adjusted
before
service
(6)
Towards the back, seat adjusted before service (6)
hints
0
checks
0
hints
The definition is at the beginning of the clue.
How the clue works
The definition is Towards the back, giving you a nautical word for at the rear of a ship. "Adjusted" tells you to anagram seat into ASTE, then tack on RN (the Royal Navy, your service) to get the full six letters.