Semi (3)
I believe the answer is:
rig
'semi' 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 "engineer or > doctor" , "Masts, spars and sails on a vessel" , "Apparatus; (boat's) sails" , "Apparatus; outfit" , "Outfit of clothes or oil-drilling platform" .)