Race Timing most often involves working with a registration. There are therefor two sets of permissions required in order to have a user who only has access to timing a single race.
First in your main club overview, go to your Permissions area
Add a new Administrator or edit an existing one to grant to “Race Timing Role” as seen below.
Being able to create a race from any registration in your account though would allow this timer access to all your registration data. This article though is how to grant access to just a specific set of data. To control this, you need to grant this user the permissions on your specific registration. To do this, go to registration, and click the More -> Advanced Settings.
Then add this user as an Authorized User on that registration and select either Read Only or Editing permission.
Now this user has permission to create races in your account, and access the registration as required. When this user goes to create a race in your account, they will only see registration to import from that they have been granted specific permissions on.