at a first glance: Microfusione seat lug, so about the same time as the cranks, second half eighties? The very sloppy lining job looks homemade.
I'm not aware whether Cinelli ever made a lower budget frame but if so, this might be one (even though the chromed lugs suggest otherwise).
There was a letter from Mr. Billato on CR list like 15 years ago in which he suggested his company had built frames for Cinelli. If so, this might actually be one?! (big speculation)