No Key signature repetition after single staff key signature change possible?

Hello everyone,
In the current piece i'm writing there is a solo cadenza in another key for which I opted to only put that intsrument into the key, however afterwards the whole ensemble modulates to that key. Is there a way to avoid the solo instrument having the new key signature twice?
(Image: so getting rid of the second A major marking only on that 1 staff.)
Thanks!