clean up
With or without an object
Make a place completely clean and tidy
Please clean up your room before your friends arrive.
With or without an object
It can be used with no object, and it can also take one. With an object it is usually separable: turn the volume up, turn it up.
The particle: up
This verb belongs to the group ‘doing it completely, to the end’.
Practise it
Add it to your daily practice or see every verb with up.
Further reading: clean up on Wiktionary (CC BY-SA).