「年なんだから無理」How does one parse this colloquial sentence?

Question

This article https://mainichi.jp/articles/20210920/k00/00m/040/036000c contains the quote

「年なんだから無理」

which I understand to mean

"The difficulties presented by your age are why it is impossible"

How does one parse this sentence? Like this?

年【とし】age

難【なん】 (n,n-suf) difficulty; trouble; hardship

だから=です+から

無理【むり】impossible

Answer 1

年 by itself can mean old age. From goo辞書

人生の盛りを過ぎた年齢。老齢。

なんだ is a form of なのだ, essentially the same as だ.

• Origin of the usage of な in ~なんだ
• コトバンク entry for なのだ

Thus 年なんだから無理 means Because (the woman is (too)) old, (her project is) impossible.

Answer 2

Sundowner's answer is good.

To build on that, I'd like to note that なのだ adds a sense of explanation that is missing from just だ. Whereas だ is basically just "[it] is", なのだ is perhaps closer to "it is because [it] is". This other post takes a deep dive into this structure in terms of grammar and meaning. This other (shorter) post contrasts the change in sense between です and （な）のです.