The raw material for a blade, by the sound of it (3)
I believe the answer is:
ore
'the raw material' is the definition.
(I've seen this before)
'blade by the sound of it' is the wordplay.
'blade' becomes 'oar' (blade is the word for oar in competitive rowing).
'by the sound of it' indicates a 'sounds like' (homophone) clue.
'oar' sounds like 'ORE'.
'for a' acts as a link.
(Other definitions for ore that I've seen before include "Valuable resource" , "Mineral aggregate" , "Natural minerals" , "tangle" , "Material for smelting" .)