filter a data.frame in dependence of a column value

Hello togehter,

i have short question, maybe anyone can help me.

I have a data.frame like this one:

       NO       ORDER
1     1530     for Mr. Muller (10.0 -> 11.2)
2     1799     for Mr Giulani
3     1888     for Mr. Marius (11.2 -> 12)

I need a solution, which only contains the values in brackets. The result should look like the following:

       NO       ORDER
1     1530     for Mr. Muller (10.0 -> 11.2)
2     1888     for Mr. Marius (11.2 -> 12)

I tried it with the following code, but that doesn't work.

data4.1<-data3[data3$ORDER%in% "[(]*->*[)]",]

maybe anyone can help me.

Thank you.

Best regards

Mat