Oil-drilling apparatus (3)
I believe the answer is:
rig
'oil-drilling apparatus' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for rig that I've seen before include "Masts, spars and sails on a vessel" , "Fit with sails and tackling" , "Manipulate; (oil exploration) apparatus" , "Fix; costume" , "Accoutre" .)