Oil cartel acronym (4)
I believe the answer is:
opec
'oil cartel acronym' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for opec that I've seen before include "Group of oil-producing countries" , "Organisation intended to control the production and sale of petroleum" , "International oil-producing cartel" , "Group of petroleum producing countries, formed in 1961" , "[CRUDE OIL] suppliers?" .)