Rights protecting expert runner (5)
I believe the answer is:
racer
'runner' is the definition.
(thesaurus)
'rights protecting expert' is the wordplay.
'rights' becomes 'rr'.
'protecting' is an insertion indicator.
'expert' becomes 'ace' (ace is a kind of expert).
'rr' going around 'ace' is 'RACER'.
(Other definitions for racer that I've seen before include "Perhaps 16 [SCRAMBLER]" , "Fast-moving snake" , "Fast driver" , "sportsman" , "Run competitor; snake" .)