Unusually veracious, apart from one piece that's bad for circulation (8)
I believe the answer is:
varicose
'bad for circulation' is the definition.
(as in varicose veins)
I don't understand the rest of the clue.
(Other definitions for varicose that I've seen before include "Knotted and swollen (of veins)" , "Dilated" , "Swollen or knotty veins" , "Of veins, permanently swollen and enlarged" , "Of vein, swollen or enlarged" .)