JAG doesn't provide any guidance on the amount of time clinical leads and training leads should be given in job planning. The amount of time must be proportional to the needs of the service and adequately cover the requirements of the role.
To support the adequate provision of time, clinical leads are encouraged to complete a diary exercise. The BMA has released a new app to assist doctors in tracking their work. More information is available at https://www.bma.org.uk/advice/employment/job-planning/dr-diary
JAG has produced some example role descriptions for clinical leads and training leads, available on the JAG website.