Tie up at a dock (4)
I believe the answer is:
moor
'tie up at a dock' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for moor that I've seen before include "Othello, perhaps" , "Fasten" , "'On Ilka - - baht'at'" , "African - wasteland" , "Secure ship with cables" .)