I found this very easy, solved in 13 mins.
Typical Quixote style, light in cultural references, homing in on the everyday experience of the solver.Simple constructions with, I think, just three complete anagrams. As always, a freshness and good surface reading to the clues.
ACROSS
1 GAS TAP - a st (abbrev for stone)in gap = opening
5 GRANGE - g = good + range = stove
10 REAGENT - Time (age) to “fill in” slit (rent).
11 RUINOUS - game = RU (Rugby Union) very common in crosswords I = one nous = common sense
13 HYDERABAD - Large city in India Definition is “city”. Rest of clue is the wordplay. Name of Park (Hyde Park in London) by r =river “to the west of” a wicked = bad. “To the west of” is used in across clues because that’s where it is when it’s written down, like here.
15 LEAR - Shakespeare’s character (and play): King LEAR. Half the students go off = Lear(ners).
25 BATHURST ISLAND Anagram of “Bird’s last haunt” with anagram indicator “destroyed”. I’d never heard of it but put “island” in on first run through, when I found the letters. After getting the other four crossing letters, I guessed right, verifying after.
27 DEMISE - is in Deme(anour) = appearance Evident is the containing indicator. Gallows humour in the surface.
DOWN
2 AWKWARD - A wk (abbrev for week) + ward (as in “ward of court”)
3 TEABERRY - ABE Lincoln (American President) in TERRY Abraham Lincoln was assassinated in 1865 and is very familiar to solvers in his abbreviated form Abe. Entertaining is the containing indicator
4 PAINTABLE - Pain (tiresome person) + table Definition is “may be portrayed”
6 ADONIS - Greek Mythology (By-word for a handsome man). Dis = the Underworld i.e. hell. So it’s “on” in “a dis”
7 GAMBOGE - Yellow resin Bomb “tossed up” = egg (reversed in a down clue) containing a + anagram “disorderly” of mob which “intrudes”
8 STARCHIEST - This was a great help in this puzzle as I solved it straightaway and it gave the starting letters of five across words because of its position. Anything with “Most” is very like to end in –est. “Archie” “hemmed in” by st and st (2 saints)
16 UNCLE SAM - Anagrams of clues, man. Personification of America. Amusing surface.
22 ICECAPS - An &lit clue. Whole clue is definition and also the wordplay . “Possibly” apices (plural of apex) indicates an anagram of it containing c = cold. In the surface reading “possibly” shows that not all icecaps are apices, but some may be. My favourite clue in the puzzle.
21 RICHES - r = King has one = I bottomless box = ches(t). Bottomless used as it’s a down clue and that’s how you see CHES in the grid.
22 ERROR - fault is definition. All the rest is wordplay.Er + roar (shout) less a
Tip: Dictionary: Indy puzzles,like daily cryptics generally,use everyday vocabulary as people will solve them while travelling etc or in breaks in the working day without a dictionary at hand. However, regular solvers will find it useful to have a dictionary to check or verify or search later, if stuck. I’d recommend the Concise Oxford English Dictionary. This should confirm all the answers and any abbreviations used.The only exception would be the occasional proper noun.