Oil producer under pressure (5)
I believe the answer is:
olive
This clue might be a double definition.
'oil producer' is the first definition.
(I've seen this before)
'under pressure' is the second definition.
The definition and answer can be both human attributes as well as being singular nouns.
Perhaps you can see a link between them that I can't see?
Can you help me to learn more?
(Other definitions for olive that I've seen before include "Greyish-green colour" , "Yellowy-green colour and fruit" , "Female" , "Fruit also used to make oil" , "Tree - shade of green" .)