Reinforced using stone once before, strong all round (9)
I believe the answer is:
bolstered
'reinforced' is the definition.
(bolstering is a kind of reinforcing)
'stone once before strong all round' is the wordplay.
'stone' becomes 'st'.
'once before' becomes 'ere' (archaic term for 'before').
'strong' becomes 'bold'.
'all round' means one lot of letters goes inside another.
'st'+'ere'='stere'
'stere' placed into 'bold' is 'BOLSTERED'.
'using' is the link.
(Other definitions for bolstered that I've seen before include "Propped up" , "support" , "Supported, strengthened" .)