Well-Greased

The term OIL WELL fits nicely into the double-definition clueing style, the two meanings being -
1. (Noun) Underground shaft that produces oil
2. (Verb) Lubricate generously

This clue appeared in today's Guardian crossword No. 24514 (Araucaria), which made use of the double-definition.
Eliminate all friction from fuel source (3, 4) OIL WELL [2]

Another similar double-definition for this term appeared in ET Crossword No. 3570 last year.
Boring to make revolution much easier? (3,4) OIL WELL [2]

And here's one more from The Hindu Crossword No. 2696, which uses a different clueing style: combination of charade + reversal + container.
Boring old Lew turned in sick (3,4) O I{LEW<-}LL

The last two clues use the same pun on the word BORING - the surface reading leads you to think of BORING(Verb)=dull, when the underlying definition is BORING(Noun)=drilled hole.

If you wish to keep track of further articles on Crossword Unclued, you can subscribe to it in a reader via RSS Feed. You can also subscribe by email and have articles delivered to your inbox.