Sailors in the shade (4)
I believe the answer is:
navy
I believe this clue is a double definition.
'sailors' is the first definition.
(group of sailors)
'shade' is the second definition.
(I've seen this before)
'in the' acts as a link.
(Other definitions for navy that I've seen before include "Armed force" , "Blue - ships and seamen" , "Ships-of-war" , "Senior service" , "Shade of the marine forces" .)