According to the Oxford Advanced Learner's Dictionary,
grind something out:
to produce something in large quantities, often something that is not good or interesting
Synonym: churn out
ex: She grinds out romantic novels at the rate of five a year.
But I think the example you posted really means this:
grind somebody down
to treat somebody in a cruel unpleasant way over a long period of time, so that they become very unhappy
ex: Don't let them grind you down.
ex: Years of oppression had ground the people down.
"clean of limb" seems to mean healthy or of good moral character, but I'm not 100% sure. I even checked in the British National Corpus and "clean of limb" is a very uncommon phrase.