While Arvin Amir's answer comes close to a full one-line solution you can drop in anywhere; he's got a slight bug in his select statement (missing the end of the line), and I wanted to handle the most common character references.
What I ended up doing was this:
SELECT replace(replace(replace(CAST(CAST(replace([columnNameHere], '&', '&') as xml).query('for $x in //. return concat((($x)//text())[1]," ")') as varchar(max)), '&', '&'), ' ', ' '), ' ', ' ')
FROM [tableName]
Without the character reference code it can be simplified to this:
SELECT CAST(CAST([columnNameHere] as xml).query('for $x in //. return concat((($x)//text())[1]," ")') as varchar(max))
FROM [tableName]