Could somebody please explain 'spendthrift' and 'having one's work cut out for one' to me?

[Tortoiseinadarkspell]

Spendthrift. Means someone who is careless or extravagant with money, right? So why is it spendthrift, which sounds like it should mean 'thrifty spender'. Is the spendthrift spending...their thrift? Or something?

And having one's work cut out means having one's task made harder. But that makes no sense, surely? I mean, the only context in which one's work would be literally pre-cut would be something like sewing, which would make it easier. Or does it mean 'cut out' as in removed? So one's work has been removed. Which is good, surely?

WHY do it mean 'made more difficult'? WHYYYYYYYY?

Spendthrift I think is from spending your 'thrift' ie spending what you've saved

On the work cut out you might try this explanation...
www.worldwidewords.org/qa/qa-wor1.htm

Wiki says (although it notes that it needs a reference that a spendthrift spends the money that was acquired by the thrift of their ancestors.

Having one's work cut out for one:

Pre-industrial-revolution, a tailor would do all parts of his job, from cutting the pattern to finishing the garment. If he had an apprentice then he could delegate part of the work, but essentially he (or she, of course) was a master craftsman and in control of the speed at which he worked.

Post-industrial-revolution, when clothes-making became a mass-production excersise, clothing workers became semi-skilled workers specialising in one aspect of the process. The people who sewed the clothes had control of the rate at which they worked taken away from them, because they could be forced to work at a higher rate by "having their work cut out for them".

I completely forgot that I started this thread. But thank you! The 'work cut out' explanation makes total sense. Spendthrift, though, is still just silly. "spends the money that was acquired by thrift", really? That was such an important sentence to convey that a word was coined?