Most listings are in the $10's per square foot per year. The Clinton submarket is experiencing a an increase in rates. In the last 3 months, the median rate rose $15 per sqft per year.
Compared to the rest of the Greater Boston market, the Clinton submarket has lower rates, so you should have no trouble finding a great deal in this depreciated submarket.
In the last 90 days, 2 listings have been listed, which means listings are probably leasing quickly. You'll want to be prepared to make an offer immediately. About 50% of the available space in the Clinton are subleases, so you might be able to find a shorter term or below market rent. There aren't many listings below 2,000 square feet available, so finding a space for a small business might be tough.
The standard measurement for office space in this area is around 1,840 sqft. Most buildings in this region are approximately 3 floors. Most buildings in this area were built in 1890 and are Class C.