Fish and chips one decides to start with (3)
I believe the answer is:
cod
'fish' is the definition.
(type of fish)
'chips one decides to start with' is the wordplay.
'to start with' suggests taking the first letters.
The initial letters of 'chips one decides' is 'COD'.
'and' acts as a link.
(Other definitions for cod that I've seen before include "One caught in the deep maybe" , "Fish; fake (colloq.)" , "to be paid for when it arrives" , "A fish; a hoax (slang)" , "North Atlantic fish" .)