Collaborating investigators changed role in case of protest (8)
I believe the answer is:
interpol
'collaborating investigators' is the definition.
I can't judge whether this definition defines the answer.
'changed role in case of protest' is the wordplay.
'changed' indicates anagramming the letters.
'case of' suggests removing the centre (like emptying a case).
'protest' with its middle removed is 'pt'.
'role'+'in'+'pt'='roleinpt'
'roleinpt' anagrammed gives 'INTERPOL'.
Can you help me to learn more?
(Other definitions for interpol that I've seen before include "Lyon-based Police Commission" , "Joined forces" , "detectives" , "Cross-border crimefighters" , "Forces cooperating" .)