Substitute goalie's first class arrangement with bank (8,5)
I believe the answer is:
standing order
'arrangement with bank' is the definition.
(I've seen this before)
'substitute goalie's first class' is the wordplay.
'substitute' becomes 'standin' ('stand-in' can be a synonym of 'substitute').
'first' suggests taking the first letters.
'class' becomes 'order' (I've seen this before**).
The initial letter of 'goalies' is 'g'.
'standin'+'g'+'order'='STANDING ORDER'
(Other definitions for standing order that I've seen before include "rise!" , "Regular way to pay" , "Instruction for bank to make regular payments" , "gets you on your feet!" , "Arrangement made with bank to pay" .)