Start relating what a would-be saver should do (4,2,7)

'saver should do' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.

'start relating what a would-be' is the wordplay.
I cannot really see how this works, but
'start' could be 'open' (opening is a kind of starting) and 'open' is found in the answer.
'a' could be 'an' and 'an' is located in the answer.
'be' could be 'count' (counting is a kind of being) and 'count' is found in the answer.
This explanation may well be incorrect...

Can you help me to learn more?