there's nothing for it

there's nothing (else) for it (but to do something)

There is only a single course of action that can achieve the desired or necessary result; there is no alternative to a certain course of action. We finally had to trade in our old, much-beloved car to buy one that had more seats and more space; with three young kids, there was nothing else for it. The virus wreaked so much damage that I'm afraid there's nothing for it but to replace the entire computer infrastructure.
See also: nothing
Farlex Dictionary of Idioms.

there's nothing (or nothing else) for it

there's no alternative. British
2002 Which? If there's nothing for it other than to get a shiny new appliance, the next question to ask is: ‘Where does the old one go?’
See also: nothing
Farlex Partner Idioms Dictionary

there’s nothing (else) ˈfor it (but to do something)

there is only one possible action in a particular situation: When the river flooded, there was nothing for it but to move everything upstairs. There was nothing for it but to try to swim to the shore.
See also: nothing
Farlex Partner Idioms Dictionary
See also:
  • nothing for it
  • there's nothing (else) for it (but to do something)
  • there's only one thing for it
  • damned if I do, damned if I don't
  • damned if you do, damned if you don't
  • I'm damned if I do and damned if I don't
  • when in doubt, do nothing
  • while you are at it
  • take action
  • action stations