Nothing written about leg cut, second-to-none (9)
I believe the answer is:
nonpareil
'second-to-none' is the definition.
(both can mean unequalled or unique)
'nothing written about leg cut' is the wordplay.
'nothing' becomes 'nil' (eg nil is zero in football).
'written about' is an insertion indicator.
'leg' becomes 'on' (cricket term, fielding positions).
'cut' becomes 'pare' (paring is a kind of cutting).
'on'+'pare'='onpare'
'nil' placed around 'onpare' is 'NONPAREIL'.
(Other definitions for nonpareil that I've seen before include "Without equal, unrivalled" , "Without equal or rival, from France" , "Matchless - enrol pain (anag)" , "A variety of apple" , "Unequalled" .)