Substitute good gold, for German the regular instruction (8,5)
I believe the answer is:
standing order
'instruction' is the definition.
(I know that standing order is a type of instruction)
'substitute good gold for german the' is the wordplay.
'substitute' becomes 'standin' (synonyms).
'good' becomes 'g' (abbreviation).
'gold' becomes 'or' ('or' is the heraldic name for gold).
'for' is a charade indicator (letters next to each other).
'german the' becomes 'der' (I've seen this in another clue).
'standin'+'g'+'or'+'der'='STANDING ORDER'
'regular' acts as a link.
This may not be correct. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for standing order that I've seen before include "Instruction to bank for payment at regular intervals" , "gets you on your feet!" , "Instruction for bank to make regular payments" , "Arrangement made with bank to pay" , "Regular way to pay" .)