Duff’s character Fiona joins siblings Lip (Jody Latham) and Carl (Elliott Tittensor) and mother Monica (Annabelle Apsion) in a mercy dash to get Frank (David Threlfall) out of his latest spot of bother.
Channel 4 are promising a “suitably Shameless finale”.
The show completes filming later this month and returns to Channel 4 in the Spring.
Speaking last year, series creator Paul Abbott said: “Its 10th anniversary seems a fitting time to shut the book on Shameless. We’ve had an absolute ball making this stuff up for a living. We’ve given back in spades and got away with absolute murder, on behalf of such a fantastically outspoken audience.”