Put a new wrapper on when you get back (7)
I believe the answer is:
recover
'get back' is the definition.
(I've seen this before)
'put a new wrapper on when you' is the wordplay.
I cannot quite see how this works, but
'wrapper' could be 'cover' and 'cover' is present in the answer.
'on' could be 're' ('on' can be mean 'with reference to') and 're' is found in the answer.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for recover that I've seen before include "Recuperate" , "Get well again" , "comeback" , "Find" , "Obtain the return of" .)