The most common and most likely answer to this crossword clue is the 5 letter word COPRA
I've seen this crossword clue in The Times
C
O
P
R
A
More clues leading to the result COPRA
- Coconut oil prepared right away, primarily from this
- Company prospector’s casing a source of oil
- Company revealed jet’s source of oil
- Key work by artist that’s a bit of a nut
- Car malfunctioning? Work inside revealing source of oil
- Leading artist – Constable perhaps – gets a source of oil
- Artist sat on by policeman is a bit of a nut
- Get painter some coconut
- Desiccated coconut?
- Capture gunner’s source of oil?
Buddy explains!

The straight part
We know that "source of oil" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case source of oil = copra.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.
What does COPRA mean?
COPRA noun- The dried kernel of the coconut, from which coconut oil is extruded.