Betting ring, or sign of animal's passing (5)
I believe the answer is:
spoor
'sign of animal's passing' is the definition.
'spoor' can be an answer for 'sign' (thesaurus). I am not certain of the 'of animal's passing' bit.
'betting ring or' is the wordplay.
'betting' becomes 'sp'.
'ring' becomes 'O' (letter resembling a ring).
'sp'+'o'+'or'='SPOOR'
Can you help me to learn more?
(Other definitions for spoor that I've seen before include "Track of wild animal" , "Animal track or scent" , "Animal's track/scent" , "Animal's track or scent" , "24 [TRAIL]" .)