Aussie bowler Fergus O'Neill completed figures of 6-72 as Nottinghamshire battled to continue to set the pace at the top of the County Championship.
Somerset had resumed on 7-295 and were all out for 310, with Archie Vaughan unbeaten on 66 as O'Neill, who had taken both openers on Friday, mowed through the visitors' tail.
The leaders also found batting difficult on their Trent Bridge wicket, their captain Haseeb Hameed removed for a four-ball duck and fellow opener Ben Slater trapped lbw for one.
