Manage northern oilfield, finally drilling well (6)
I believe the answer is:
handle
'manage' is the definition.
(I know that manage is a more specific form of manipulate)
'northern oilfield finally drilling well' is the wordplay.
'finally' indicates one should take the final letters.
'drilling' indicates putting letters inside (inserted letters drill through others).
'well' becomes 'hale' (I've seen this before).
The final letters of 'northern oilfield' are 'nd'.
'nd' going inside 'hale' is 'HANDLE'.
(Other definitions for handle that I've seen before include "Manage - name" , "Deal with; name (colloq.)" , "Manipulate; name" , "Cope with" , "Touch - deal with" .)