Hard physical work (5,6)
'hard physical work' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for elbow grease that I've seen before include "Vigorous physical effort" , "Hard rubbing (colloq.)" , "Hard physical effort" , "Hard physical work (informal)" , "Vigorous physical labour involving hard rubbing" .)
'hard physical work' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for labour that I've seen before include "Old political party?" , "Workers" , "Agonising time" , "opposition" , "End of term" .)