為さい is read as なさい (nasai) and means do ....
なさい
nasai
しいしい
while doing over and over
かわせ
exchange (e.g. foreign)
ため
affecting
いせいしゃ
statesman
かわせそうば
exchange rates
なす
to change into
なさる
to do
かわせかんり
exchange control
かわせぎんこう
exchange bank
ために
because of
いこうかい
Iko-kai (faction of the LDP)
いせいか
politician