17 across
An
essential
for
burner
of
midnight
oil
hit
spot
(9)
An essential for burner of midnight oil hit spot (9)
hints
0
checks
0
hints
The definition is at the beginning of the clue.
How the clue works
Right, so An essential for burner of midnight oil is your definition — basically what you'd need if you're working through the night. For the wordplay, "hit" gives you LAMP, since to lamp someone means to hit them, and "spot" gives you LIGHT, as in "I spot" or notice something — stick LAMP and LIGHT together and you're there.