Order fish provided by chippy finally (6)
I believe the answer is:
codify
'order' is the definition.
(thesaurus)
'fish provided by chippy finally' is the wordplay.
'fish' becomes 'cod' (cod is a kind of fish).
'provided' becomes 'if'.
'by' means one lot of letters go next to another.
'finally' says to take the final letters.
The final letter of 'chippy' is 'y'.
'cod'+'if'+'y'='CODIFY'
(Other definitions for codify that I've seen before include "Systematise" , "Arrange laws or rules into set" , "Collect and classify" , "Order" , "Arrange systematically" .)