Hi,
Speaking about Age limit in fashion designing, there is in fact no such thing. But, still, the upper age limit might be subject to restrictions in some colleges or institutes.
But you must have a calling for it!
This means as this is a creative career, even if you take it up as a hobby or something, you must fulfill the other eligibility criteria as well to get yourself admission to the best colleges.
Now, it will completely depend upon the individual colleges and the age criterion they have set for the candidates.
Therefore, I recommend you must thoroughly check with the individual colleges.
And, if you are asking this question because you think age-wise it is a bit late to start..... Remember "You are not old to learn new things", that too when your heart goes out for it... So follow your heart to follow your dreams.
Still, if your age is way over the upper age limit criteria, you must search for colleges and institutes where you might go for some diploma along with internships, etc, and after that, you may pursue the Master(PG) Fashion Designing Courses. So you have to follow the eligibility criteria at every step. So, in this case, you have to move ahead with a plan to pursue your dream career, complete the whole course in the shortest available time, get the best placement, and make the best out of the opportunity.
All the Best!