Jack (5)
'jack' is the definition.
(knave can mean a jack playing card)
This is the entire clue.
(Other definitions for knave that I've seen before include "Unscrupulous man; jack" , "Rascal; picture card" , "Jack (in playing cards)" , "A swindler" , "Blackguard" .)
'jack' is the definition.
(both are informal terms for sailor)
This is the entire clue.
(Other definitions for tar that I've seen before include "Product of coal" , "Black substance, used on roads" , "Product of burning tobacco" , "Sailor; road surface" , "Slang sailor or road surfacing material" .)