Crew member
There are a few possibilities for this:
'crew member' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for oar that I've seen before include "Rowing implement" , "Use it to move a boat" , "Boat propellant" , "I'm involved in row" , "Rower's paddle" .)
'crew member' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for tar that I've seen before include "Sticky road material or informal sailor" , "Product of smoking cigarettes" , "Sticky substance - seaman" , "Mariner, old salt" , "Jack < to blacken" .)
'crew member' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for cox that I've seen before include "He's in charge of a racing boat and its rowers" , "Steerer of oarsmen in rowing boat" , "Steersman" , "Helmsman" , "Boat's steerer" .)