To drop an apple core in the dirt would do it no good! (5)
I believe the answer is:
spoil
'dirt would do it no good' is the definition.
I can't tell whether this defines the answer.
'to drop an apple core in' is the wordplay.
'to drop' becomes 'soil' (I can't justify this - if you can you should believe this answer much more).
'core' says to take the centre.
'in' means one lot of letters goes inside another.
The middle letter of 'apple' is 'p'.
'soil' enclosing 'p' is 'SPOIL'.
'the' acts as a link.
Can you help me to learn more?
(Other definitions for spoil that I've seen before include "Treat overindulgently" , "Mess up" , "decompose" , "Cook" , "Harm or destroy" .)
