removing character from string (regular expresion)

[Sayed, Irfan \(Irfan\)]

Hi All,
 
I have one variable $feature which contains value as "feature level: 2".
Now i need to remove "feature level: " and need only 2 as a output.
 
I mean from the value "feature level: 2" i need only 2. Basically i need
to trucate/remove "feature level: ".
 
I tried in the following way
 
$feature = s/feature level: //g;
 
but the value of $feature is not 2.
 
Can anybody please help.
 
Regards
Irfan.