1: Extend a term of imprisonment (7)
3: ...hence, in this place, furnishings initially included in rent (9)
4: Trespass upon a moniker exploited by commercials (4,7)
6: Go over and bring harness-racing horse back (5)
7: Odysseus' first requirement - to catch you like Polyphemus? (3-4)
8: Rub the wrong way with quietly mixed drink, leading to uncontrollable gas problems. (7)
10: Freeze one mug filled with tea, essentially (3,2)
13: Everyone in Italy's mad - so it's said - for ice cream (5-6)
15: Sad, sad strands of Gershwin tunes, for instance (9)
17: A legendary string player, he joins us after turning professional (7)
18: Jay and I invested in lard-like snacks (7)
20: Private dinner starts late (5)
21: 'Naked Gun' actor prepares to be dubbed in (in soundtrack) (7)
23: Boxer Max returned, holding heroin, for treatment (5)
25: Cull out from top ten (3)