ACROSS

 1  Of, of, of, of, of, of, of, of, of, of. (10)

 6  This place seems best in retrospect. (4)

10  I’m coming back when you have the proper sort of candy around. (7)

11  Speak illy, as of itself. (7)

12  Timeless average. (4)

13  Seldom seen without a date, hence often short? (4, 6)

15  Hamlet should contain this kind of cheese. (7)

16  Retired shortly, with a pained expression. (7)

17  The meaning of this is not clear. (7)

20  In favor of something to denote action? (7)

22  Is France in the proper position to expose them? No! (10)

23  Ripe for a change. (4)

25  Beat it! (7)

26  Overcome by force. (7)

27  How a dance winds up? (4)

28  Graduated with many degrees. (10)

DOWN

 1  His arms are rather long and powerful. (8, 7)

 2  Sunburned fellow? (7)

 3  Yes, you are both contrary in Alaska. (4)

 4  Perfume to excite. (7)

 5  How our name is changed. (7)

 7  Neighborhood. (7)

 8  Did they charge for electricity? (3, 5, 7)

 9  Change a prop into something which sounds apart. (9)

14  Sounds like a baseball team is only half-human, but gloomy. (9)

18  How the committee stands when it hasn’t time to sit. (4, 3)

19  Does this look bad? (4, 3)

20  Priests persevere, naturally. (7)

21  Did she look well in black? (7)

24  Had a meeting with the Titanic. (4)