British boy starts to engrave steel swords (6)
I believe the answer is:
blades
'swords' is the definition.
('blade' can be a synonym of 'sword')
'british boy starts to engrave steel' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in BBC).
'boy' becomes 'lad' (informal term for boy).
'starts to' indicates taking the first letters.
The first letters of 'engrave steel' is 'es'.
'b'+'lad'+'es'='BLADES'
(Other definitions for blades that I've seen before include "Leaves of grass or cutting tools" , "Football club nickname" , "Metal runners on skates" , "cutters" , "They cut" .)