Pet held by French student (5)
I believe the answer is:
cadet
'student' is the definition.
(I have seen 'Military student ' mean 'cadet' so perhaps 'student' could also mean 'cadet')
'pet held by french' is the wordplay.
'pet' becomes 'cat' (cats are often kept as pets).
'held' indicates putting letters inside.
'by french' becomes 'de' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'cat' placed around 'de' is 'CADET'.
Can you help me to learn more?
(Other definitions for cadet that I've seen before include "Potential officer" , "Junior officer; younger brother" , "Police force trainee" , "One taking instructions" , "Military student" .)