Cryptic crossword No 3,933

Down

• 1 downShake-up in a UK lab reaching a peak (8)
• 2 downKing perhaps, who famously played princess? (6)
• 3 downStronghold in East regularly delivers ten year stretch (7)
• 4 downMuck about with Iona? He's getting to grips with future wife (8)
• 5 downScandinavian settler has money lender's interest - family imprisoned (6)
• 7 downThey blow up some diesel again (5)
• 9 downChanging course and mocking justice to become victor (7)
• 16 downBroadband for rock group? (7)
• 17 downPattern of wind that's coming round again - groan loudly, then call for enema! (8)
• 19 downPlatforms demanding angriest nuts! (8)
• 20 downOld spirits imbibed at the outset - made woozy at heart, somewhere over Scotland (7)
• 22 downAccepted kiss from Gaelic employee - extremely high point (6)
• 24, 27a downArea where lecturer leaves donuts with indignation after shout-out (5,6)
• 25 downContinue with summary (6)