Two ways to rank second bank’s services (8,6)
I believe the answer is:
standing orders
'bank's services' is the definition.
Although both the answer and definition are plural nouns, I don't see how they can define each other.
'two ways to rank second' is the wordplay.
'two ways' becomes 'standing' (I can't justify this - if you can you should give a lot more credence to this answer).
'to rank' becomes 'order' ('order' can be a synonym of 'rank').
'second' becomes 's' (common abbreviation).
'standing'+'order'+'s'='STANDING ORDERS'
(Other definitions for standing orders that I've seen before include "rules of procedure" , "Procedural rules" .)