Ruler of China erodes another’s borders (6)
I believe the answer is:
caesar
'ruler' is the definition.
(Julius Caesar)
'china erodes another's borders' is the wordplay.
I cannot really see how this works, but
'another's' could be 'es' (I've seen this in other clues) and 'es' is found in the answer.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for caesar that I've seen before include "Julius, stabbed by Brutus" , "See 2" , "Old Roman emperor like Julius" , "Taking little bites" , "Roman ruler" .)