Body part of cat probed by a practitioner, ultimately (6)
I believe the answer is:
larynx
'body part' is the definition.
(larynx is a kind of body part)
'cat probed by a practitioner ultimately' is the wordplay.
'cat' becomes 'lynx' (lynx is a kind of cat).
'probed by' indicates putting letters inside (I've seen this in other clues).
'ultimately' indicates one should take the final letters.
The last letter of 'practitioner' is 'r'.
'a'+'r'='ar'
'lynx' enclosing 'ar' is 'LARYNX'.
'of' acts as a link.
(Other definitions for larynx that I've seen before include "Location of vocal cords" , "part of neck" , "box for speaker" , "Air passage" , "Creator of speech" .)