$VAL = join '', map { /^\*\s\(?([^\)]+)\)?/ ? $1 : '' } @GET_STRING;

##</code><code>##

>perl -wMstrict -le
"my @GET_STRING =
   ('no', '*nine', '*(not)', '* yes', '* (yup)', '* ya)');
 ;;
 my $VAL = join '', map { /^\*\s\(?([^\)]+)\)?/ ? $1 : '' }@GET_STRING;
 print qq{'$VAL'};
"
'yesyupya'