International organisation cleared out petrol refined by government to remove the lead (6)
I believe the answer is:
unplug
'remove the lead' is the definition.
(as in unplugging an electrical lead)
'international organisation cleared out petrol refined by government' is the wordplay.
'international organisation' becomes 'UN' (United Nations).
'cleared out' says to hollow out the word (remove centre letters).
'refined' becomes 'u' (abbreviation for upper-class - opposite to non-U).
'by' is a charade indicator (letters next to each other).
'government' becomes 'g' (abbreviation for government).
'petrol' with its middle taken out is 'pl'.
'un'+'pl'+'u'+'g'='UNPLUG'
'to' is the link.
(Other definitions for unplug that I've seen before include "Disconnect (kettle or toaster?)" , "Disconnect (an electrical device)" , "Disconnect from power" , "Remove a blockage from" , "Remove from a socket" .)