Clean task not found in gradle

I have a gradle build file and I cannot complete the build. I am working with old code, and the code must be built with the version 1.0-milestone-7, as other projects use this version.

apply plugin: 'idea'
apply plugin: 'java'
apply plugin: 'base'
apply plugin: 'application'

assert gradle.gradleVersion == '1.0-milestone-7'

mainClassName = "my.ClassTest"

buildscript {
    repositories {
        mavenLocal()
        mavenCentral()
    }
}

test {
    systemProperties = System.properties
}


c:\work\gradletest\> gradle clean
FAILURE: Could not determine which tasks to execute.

* What went wrong:
Task 'clean' not found in root project 'gradletest'.

* Try:
Run gradle tasks to get a list of available tasks.

Anything I forgot?