It has a clear enough meaning and the history of the word goes back nearly 600 years with little change, yet the etymology is uncertain. The OED has several guesses listed, but none is quite satisfactory. Delightfully, the original word appears to have been used in conjunction with the word "in" or "on" preceding it and only gradually shifted into the attached prefix "a-".
Well, I think it's delightful.
akimbo, adv. and adj.
a. With hands on hips and elbows turned outwards.
b. With reference to (other) limbs, esp. the legs: spread or flung out widely or haphazardly.
2. More generally: askew, awry; in disorder.
Crooked, bent, or askew; that is in disorder, awry.