Custom legislation included in the cost of goods (8)
I believe the answer is:
practice
'custom' is the definition.
(I've seen this in another clue)
'legislation included in the cost of goods' is the wordplay.
'legislation' becomes 'act' (I've seen this before).
'included in' means one lot of letters goes inside another.
'the cost of goods' becomes 'price' (I can't justify this - if you can you should believe this answer much more).
'act' placed into 'price' is 'PRACTICE'.
Can you help me to learn more?
(Other definitions for practice that I've seen before include "Routine" , "Professional business of doctor or lawyer" , "The exercise of a profession" , "Exercise; professional business" , "Use" .)