A deputy, the beast, having a snoop round (5)
I believe the answer is:
proxy
'a deputy' is the definition.
(thesaurus)
'the beast having a snoop round' is the wordplay.
'the beast' becomes 'ox'.
'having a snoop' becomes 'pry' (I can't explain this - if you can you should believe this answer much more).
'round' indicates putting letters inside.
'ox' put inside 'pry' is 'PROXY'.
Can you help me to learn more?
(Other definitions for proxy that I've seen before include "Authorised deputy" , "Authority to represent others" , "Agent (for eg voting)" , "Authorised substitution" , "Person authorised to act on behalf of another" .)