I have friends who have been eventually cleared for CAT1A roles last year with HR telling them it will take up to 6 months - most took around 3-4 months though. but if yours is an average clearance, then it should definitely be faster. Also, most people DO pass security clearances unless you have relatives working in foreign govt (they check even the long dist ones).

Dec (even early Jan) is usually a quiet month where people are clearing their annual leaves so that may delay things further and Oct was also when COVID cases hit their peak so you can imagine how that has affected the workflow.

if anything, communicate with the HR people - they are more than happy to help you. all the best!