Docking spot (4)
'docking spot' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for pier that I've seen before include "A landing stage or promenade" , "Mole, wall between windows" , "Bridge pillar" , "Seaside platform" , "Support member" .)
(Other definitions for quay that I've seen before include "Dock's loading area" , "Some of port" , "Jetty" , "Landing-place" , "Whatf built parallel to the shoreline" .)