Inject copper into misshapen toenail (9)
I believe the answer is:
inoculate
'inject' is the definition.
(inoculating is a kind of injecting)
'copper into misshapen toenail' is the wordplay.
'copper' becomes 'Cu' (Cu is the chemical symbol for copper).
'into' indicates putting letters inside.
'misshapen' indicates an anagram.
'toenail' with letters rearranged gives 'inolate'.
'cu' placed within 'inolate' is 'INOCULATE'.
(Other definitions for inoculate that I've seen before include "Inject against a disease" , "Immunise with antigens" , "Induce immunity" , "Graft" , "Treat with a vaccine or serum" .)