ACROSS

 1  and 15 and 17 down Throw in a few more chips! (7,3,3)

 5  See 3 down

 9  Return one of the colors to the row which is sharper! (7)

10  Fancy building this! (7)

11 , 12 and 13 What the detective and the shortstop might be expected to do and meet the answer. (5,3,5)

14  They don’t offer much time for what started the scale long ago to be in the pits, but they might be taken from the meeting. (7)

16  Get me back on track, with your beginning to have a vicarious experience. (7)

18  One might hope such are well oiled, unless they typify those who praise fulsomely. (7)

21  You expect the wine not to be what the garden should be. (7)

24 , 26 and 31 High fliers that could do lots of damage, although excellent for your hair! (5-10)

27  and 1 down That special space of yours. (5,7)

28  One typical of a whole class, with a slice of pie given to me. (7)

29  Has proven wrong when sleeping around–being somewhat embarrassed. (7)

30  Old Persian monarchs took the chair with what many a modern entertainer does. (7)

31  See 24

DOWN

 1  See 27 across

 2  Get on board, because 10 is confused over the downpour. (7)

 3  and 5 across A choice offering around the end of October. (5,2,5)

 4  Mailer’s French conquerors. (7)

 5  Possibly a fine result from books being so! (7)

 6  One from Baghdad was famous–or infamous. (5)

 7  How we are told certain truths may be, self-started. (7)

 8  Possibly a duet, say–with the middle of the week approaching! (7)

15  and 17 See 1 across

18  Gets set about what the ship may say before its name, being set inside–and they may improve the fit. (7)

19  A second-year student starts to sit improperly, being somewhat of a thinker. (7)

20  Frequently found between two points, and makes things less hard. (7)

21  Wild talk about fighting? Vouch for it! (7)

22  They might be typified by the Ponderosa for some people, being operated by the revolutionary to the South. (7)

23  Desired wrongly to show what the mocker does. (7)

25  You can’t say this girl doesn’t have a hoard made up! (5)

27  Kinda stupid, in a Northeast way. (5)