Animal implant — note reptile with it (9)
I believe the answer is:
microchip
'animal implant' is the definition.
'note reptile with it' is the wordplay.
'note' becomes 'mi' (as in 'do re mi').
'reptile' becomes 'croc' (I've seen this before).
'with it' becomes 'hip' (I've seen this in other clues).
'mi'+'croc'+'hip'='MICROCHIP'
(Other definitions for microchip that I've seen before include "Bit of hardware" , "processor?" , "produced in Silicon Valley?" , "Integrated circuit" , "Tiny proportion of potato" .)