Reclaim space from dropped column in SQLServer2008R2
I did more work on the subject and came up with an interesting insight.
Working with the Express edition database engine, I just dropped the column, re-indexed the primary key (cluster index) to re-arrange the data, which inflated the database file size to more than 10Gb and then simply performed a shrink step (NOTRUNCATE) to compact the database file and reduce it's size within nominal limits. 
The database engine didn't complain for the excess size during this process and the end result was a database file that had the space needed reclaimed. 

So I guess the answer was simpler to solving the problem at hand.

However I still remain puzzled about CLEANTABLE not doing what the documentation describes it does.