in the 1st place, u should not let him catch ur leg ah...
i personelly feel, mayb u kick too soft so he can hold ur leg
..
so now, we gv u benifit of doubt tat u kick very powerful, jus tat
he happen to catch/hold ur leg, its time u gotta learn some ground
fighting...take BJJ for example.Make a search for it, den go from
there.
Or, if u jus wan simple way out, use ur leg power to force ur leg
down, be prepare to use hand to guard a blow from him, or take his
punch, den whack again.
of if u are fast enough, when he grap ur leg, "at the point in time
when u exert force on ur leg to pull down to ground,use the
momentium to life ur left leg & kick him, tat should do it.But
be prepare to fall down also, if u cannot balance.
wat i feel is dun fight....fight for wat, earn $$ better...den take
$50 give bangala, den point to te guy u hate, tel him, beat beat..
can liao..
or u see when he alone,attack from behind, u can emerage victory in
a easier way. 
