Money private investigator gets initially finding pet (6,3)
I believe the answer is:
guinea pig
'pet' is the definition.
(I've seen this before)
'money private investigator gets initially' is the wordplay.
'money' becomes 'guinea' (I've seen this before).
'private investigator' becomes 'PI' (abbreviation).
'initially' indicates taking the first letters.
The first letter of 'gets' is 'g'.
'guinea'+'pi'+'g'='GUINEA-PIG'
'finding' is the link.
(Other definitions for guinea pig that I've seen before include "Animal like rat or person used for experimentation" , "One experimented upon" , "Animal (used in experiments?)" , "rodent eaten in Peru" , "Person in trial" .)