Is said to be ordered in advance (8)
I believe the answer is:
bespoken
'ordered in advance' is the definition.
'bespoken' can be an answer for 'ordered' (I've seen this before). I am unsure of the 'in advance' bit.
'is said to be' is the wordplay.
'is said' becomes 'spoken' (I've seen this before).
'to' says to put letters next to each other (I've seen this in other clues).
'spoken' after 'be' is 'BESPOKEN'.
Can you help me to learn more?
(Other definitions for bespoken that I've seen before include "Pre-arranged" , "Ordered" .)