Like J.R., I don't see a good match between the language of the quoted sentence and any clear, recognized definition of churning.
The only definition of "churning away" that I'm familiar with carries a sense of purposeless activity; essentially it means "churning without a definite goal or foreseeable end," as in "He left the refrigerator door open, and the motor was just churning away all afternoon."
"Churning away" emphatically does not mean churning productively—not even at the impersonal, quota-driven level of "churning out," which, as Merriam-Webster's Eleventh Collegiate notes, involves "produc[ing] mechanically or copiously," but which frequently harbors an implication of poor or indifferent quality in the resulting output.
Making sense of the author's description of women churning away "dreams, fears, social [intrigues] and political intrigues" is complicated by the fact that one of the churned-away things (dreams) seems desirable, a second (fears) seems undesirable, and a third (intrigues) may be desirable or undesirable. Under the circumstances, it's hard to tell whether the women intend the churning to produce these things—or indeed whether the women have any clear intention at all with regard to their churning.
Maybe the author chose "churning away" to avoid the unflattering implications of "churning out." If so, I think it was a bad decision, since "churning away" does an exceedingly poor job of conveying what (I suspect) the author means. I would have suggested ending the sentence as follows:
...where the women of the home give voice to dreams and fears, and where elaborate social and political intrigues play out."
An author determined to tie the sentence to a kitchen-friendly verb could have used "cook up" or "brew up." Both have weaknesses of their own—"cook up" suggests fabrication of a deceptive kind, and "brew up" has witchy connotations—but at least they aren't borderline nonsensical, as "churn away" is.
Best Answer
I've come across this usage, but I can't find it in the usual online dictionaries (Lexico, Collins, AHD, CED, M-W ...). I remember the expression 'young cannon', so I've searched for this.
From an article from 'The Authentic Campaigner', reviewing Three Years in the Confederate Horse Artillery (tidied) by George Neese:
The poster comments:
So a 'not quite' cannon.
A downtoner usage, not an intensifier. An archaic (the Christie example probably thwarts the 'obsolete' labelling) usage, but still sounding better than say 'He had what could almost be considered an arsenal with him.'