Ordered to include large part of oar (5)
I believe the answer is:
blade
'part of oar' is the definition.
('blade' is part of 'oar')
'ordered to include large' is the wordplay.
'ordered' becomes 'bade' (I've seen this before).
'to include' is an insertion indicator.
'large' becomes 'l'.
'bade' going around 'l' is 'BLADE'.
(Other definitions for blade that I've seen before include "cutter" , "Cutting edge" , "Runner on an ice-skate" , "See 24 Across" , "Flat part of an oar" .)