Checked by a doctor (6)
I believe the answer is:
vetted
'checked by a doctor' is the definition.
I can't tell whether this definition defines the answer.
'checked by a doctor' is the wordplay.
'checked' becomes 'ted' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'by' is a charade indicator (letters next to each other).
'a doctor' becomes 'vet' (vet is a kind of doctor).
'ted' put after 'vet' is 'VETTED'.
Can you help me to learn more?
(Other definitions for vetted that I've seen before include "Checked carefully" , "Security-checked" , "Examined and passed" , "Thoroughly checked" , "Investigated (someone) thoroughly" .)