give (someone their) head

to allow someone the freedom to do what they want.

He's got some great ideas. Why not give him his head and see what kind of campaign he comes up with.

• the wheels are turning
• the whole ball of wax
• the whole bit
• the whole caboodle
• the whole enchilada
• the whole kaboodle
• the whole kit and caboodle
• the whole nine yards
• the whole picture
• the whole shebang
• the whole shooting match
• the whole works
• the whys and the wherefores
• the whys and wherefores
• the whys and wherefores of
• the whys and wherefores of something
• the witching hour
• the woman in the street
• the woman of dreams
• the woman of your dreams
• the woman on the Clapham omnibus
• the woman on the street
• the wooden spoon
• the works
• the world and his wife