Across

1. Bound cheat extracted (11)
          CON  STRAINED
5. Delaware West - secret drink (3)
    ELA [reversal] [hidden]        [ELA reversed is ALE]
7. Remote central European mockery (5)
   FAR      C        E
9. What is non sufficit, is not, for eye (3)
   non sufficit ORBIS     -IS      [James Bond's motto translates to The World Is Not Enough]
10. Contains record, "Lost vessel sails east rather than south" (6)
             [anagram flag]
    [replace an S in vessel with E, and jumble to get SLEEVE, which is what a record's case is called]
12. American effort - mixed objective, a rove (8)
    [spelling]    [anagram]    END     A ROVE
13. Suspicious smell - Laura traced it to the maddening competition (3-4)
      smell a RAT      lauRA TRACEd                         RACE
14. Like an ape is an amputated primate (6)
                IS AN [dismember] IM    [dismember = chop off arms, in a sense!]
18. My ring pictures very little (6)
    MY   O  PIC      [part of word]     [Here, 'myopic' means 'lacking imagination']
20. Let splendour ring us in vain (7)
          POMP     O   US [charade flag]
22. Gore sounds stringed (8)
      [homophone] VIOLINS [sounds like VIOLENCE]
24. Values of the depraved in word or deed (6)
                  [anagram]        ERODED [The depraved have eroded values]
25. Record French sound backwards (3)
            GAUL  [homophone = GOL = LOG backwards!]
26. Would seem to be basement in nalp (5)
    [An attic would seem to be the basement in an inverted plan (nalp). 
    Actually, it would be so in an inverted elevation, but plan is a general enough term, I suppose!]
27. Hit the groove (3)
    [Double Definition : hit = RAP; the groove is a term associated with RAP music
    RUT is also an acceptable word, though it isn't quite what I had in mind.]
28. Past actions before frantic descent (11)
                  ANTE [anagram] CEDENTS

Down

1. Save crazy talk for later (8)
    [anagram] CONVERSE -> CONSERVE
2. Note: tiny pole doesn't matter (3-6)
   NOTE  TINY N   [jumbled]
3. Little known facts about endless trip and bottomless container (6)
                        [truncated] TRIp [charade] [truncated] VIAl
4. Void article in crown of emperor (5)
           AN   IN [first letter]  E
6. Decapitated organ leaves almost extinct residue of activity (5)
   [minus first letter]  mEMBER
8. An ill-bred gambler's cube assists gentleman (6)
        CAD        DIE
11. Kings almost mystic (4)
      [truncated]  MAGIc
15. Harmony and charge is played (9)
    ACCORD [charade]  ION
16. Seal sounds like ugly duckling (6)
      [homophone]  [young swan = CYGNET sounds like SIGNET]
17. Sin rides members of secret circle (8)
    INSIDERS
19. Eye jumbled blocks (4)
      [anagram]   LEGO(!)
21. Sickly offer endlessly more (6)
            BID [truncate] MORe
22. Sicker liver (5)
    [anagram] VILER
23. Cream ignited in electrical medium (5)
            LIT [container]   EE(!!)