ACROSS

1 Might keep releasing energy, surely (3,7) FOR CERTAIN
FORCE + RETAIN minus E(nergy)

6 Shower used to be hot (4) WASH
WAS + H(ot)

9 Touch-related piece of technology next to concrete (7) TACTUAL
T(echnology) + ACTUAL

10 Cry out, beginning to experience unusual climax (7) EXCLAIM
E(xperience) + anag. of CLIMAX

12 Make better urchin stray (7) IMPROVE
IMP (urchin) + ROVE (stray)

13 Reportedly carries off troubadours' instruments (5) LUTES
Homophone of LOOTS (carries off)

15 Originally, Victoria cuts climbing plants (7) VETCHES
V(ictoria) + ETCHES

17 Chief of Navajos wearing fancy dress (7) GARNISH
N(avajos) wearing GARISH

18 Cut grass surrounding 1/3 of ducklings (7) REDUCED
REED (grass) around 1st 3 letters of DUC-klings

21 Comparatively arrogant spaniel wins, one (7) COCKIER
COCKER around I

23 Up to hunt illegally for a stretch (5) UNTIL
Hidden

24 Shows its age, moving slowly around back of cave (7) YELLOW
Anag. SLOWLY + (cav)E

27 Process reddens 1945 bombing site (7) DRESDEN
Anag. REDDENS

28 He doesn't appreciate where a fire may be lit (7) INGRATE
Cryptic definition

29 Bill perceives sounds (4) NOSE
Homophone of KNOWS

30 In the end, inventory includes most of fur (10) TERMINALLY
TALLY around most of the word ERMIN(e)

DOWN

1 Female swallowed up Greek cheese (4) FETA
F(emale) + ATE rev.

2 Acknowledgment usher once again heard (7) RECEIPT
Homophone of RESEAT

3 Outfit ultimately tore on barb (5) EQUIP
(tor)E + QUIP

4 Famous model approves fats for candles and soap (7) TALLOWS
Model T + ALLOWS

5 Variety of lettuce provided by Candice Bergen (7) ICEBERG
Hidden

7 Showy flowers can't fit into sushi's tuna (7) ACANTHI
CANT inside AHI

8 Half of globe is overwhelmed by fibre at this point (10) HEMISPHERE
HEMP over IS + HERE

11 Twisted car coil driven by heat (7) CALORIC
Anag. CAR + COIL

14 Oppress something that may be irregular in our reading room (10) OVERBURDEN
VERB (that may be irreg.) inside OUR + DEN (reading room)

16 Dickens was up front, harassed by the audience (7) HECKLED
HECK (expletive) + LED

19 Bumstead's boss hits red convertible (7) DITHERS
Anag. HITS + RED

20 Senior woman finished going around Japanese capital (7) DOYENNE
DONE around YEN

21 I expressed hesitation after Calvin Coolidge's inaugural element (7) CALCIUM
I + UM after CAL(vin) + C(oolidge)

22 Stalin juggled large load (7) INSTALL
Anag. STALIN + L(arge)

25 Letting loose groan, pipes up in church? (5) ORGAN
Anag. GROAN

26 Count only just missing Bachelor of Arts (4) RELY
BARELY minus BA