On a 2001 Ford Focus : The brake fluid reservoir is used for the brake and clutch systems
by unscrewing it.
The brake fluid reservoir is mounted on the Master Cylinder. Drivers side near the firewall.
See answer on "How do you change the front brake pads on a 2001 Ford Focus?" for a description of the location of the resivoir. The answer to this exact location is at the bottom of that answer.
It uses brake fluid in the brake fluid reservoir. The clutch fluid (brake fluid) is fed by the brake fluid reservoir. The clutch fluid reservoir is just beneath the brake fluid reservoir. So, add fluid to the brake fluid reservoir to fill the clutch fluid, also.
To put brake fluid in a Ford Focus, you need to locate the master cylinder, which should be on the drivers side under the hood. On this , you'll find the brake fluid reservoir. You unscrew the cap and replenish using the right brake fluid, and screw the cap back on.
The brake fluid reservoir
On a ( 1996 ) Ford Escort the brake fluid reservoir is also the clutch fluid reservoir
Use a turkey baster or something similar to empty the brake fluid reservoir as much as possible. Open the wheel bleeder valves and drain the lines. Refill the system, then bleed the lines on the Ford Focus.
On a 2006 Ford Escape : The brake fluid reservoir is also the clutch fluid reservoir
On a 1995 Ford Escort : The brake fluid reservoir is also the clutch fluid reservoir
If it is like the ( 1996 ) Ford Escort : The BRAKE FLUID RESERVOIR is also the CLUTCH FLUID RESERVOIR