Tories' top minister lacking means to gain goodwill for CO (7)
I believe the answer is:
teacher
'co' is the definition.
Although both the answer and definition are singular nouns, I don't understand how one could define the other.
'tories' top minister lacking means to gain goodwill' is the wordplay.
'tories' top' becomes 't' (I can't justify this - if you can you should believe this answer much more).
'minister' becomes 'preacher' (someone who preaches).
'lacking' indicates named letters should be taken away.
'means to gain goodwill' becomes 'PR' (public relations).
'preacher' with 'pr' taken out is 'eacher'.
't'+'eacher'='TEACHER'
'for' acts as a link.
(Other definitions for teacher that I've seen before include "School educator" , "one of the staff" , "Cheater (anag.)" , "Member of school staff" , "One who educates" .)