You can find links to the crossword here and the answers below. Feel free to leave any comments or questions here as you would do on TfTT.
[Solution (click to open)]
Definitions underlined in bold italics, (Abc)* indicating anagram of Abc,
1 Johninterred's one weird tester (6)
SETTER - [weird] (tester)*.
4 School-leaver rankings provided by A&E, for example. (6)
GRADES - Cryptic definition. Go to hospital to take your exams? Teacher knows best, allegedly.
8 Oliver's request for another card (5)
TWIST - Doublde deinition. "Please Sir, Can I have some more?" or another card at pontoon.
9 Postie's equipment is reportedly a manly accessory (7)
MAILBAG - Sounds like (reportdely) MALE (manly) BAG (accessory).
10 Some thinkers fill pens with this (3)
INK - Hidden [some] in thINKers.
11 Grins anew about refuting an argument (9)
ANSWERING - (Grins anew)* [about].
12 Foreign variety of dressing that goes with beans and toast? (6)
FRENCH - Definition and a cryptic hint - French Beans, French Toast.
13 Unfaithful? Not according to the facts (6)
UNTRUE - Double definition
16 Reinvents career, set to be different (9)
RECREATES - (career set)* [to be different].
18 Author of "The Female Swan" (3)
PEN - Double definition.
19 Cross-channel invaders were no loveless Romans (7)
NORMANS - NO R
20 Initially amazed this once meant smallest fundamental particles (5)
ATOMS - First letters of (intially) Amazed This Once Meant Smallest.
22 Firstborn of the French captured by English lieutenant (6)
ELDEST - DES (of the, in French) [captured by] E (english) LT (lieutentant.
23 "Redo it!", ordered crossword compiler's boss (6)
EDITOR - (Redo it)* [ordered].
1 Take a test model (3)
SIT - Double Definition.
2 Try to catch trout in river? On the contrary! It's just a little stream (7)
TRICKLE - TICKLE (try to catch trout) outside not [in] [on the contrary] R (river).
3 You may have to pass these to get into school (8,5)
ENTRANCE EXAMS - Cryptic definition.
5 Threaten to strike if you want to say something in class (5,4,4)
RAISE ONES HAND - Cryptic definition.
6 Name a single luxurious Arab destination (5)
DUBAI- DUB (name) A I (one; single).
7 Tone of wise environmentalist (4-5)
SAGE GREEN - SAGE (wise) GREEN (environmentalist).
9 Fail to understand teacher (4)
MISS - Double definition.
10 Drawing a conclusion in conference without counter argument (9)
INFERENCE - IN
14 Hit wine together to make emotional bond (7)
RAPPORT - RAP (hit) PORT (wine).
15 Aussie pick-up trucks regularly found among gum trees (4)
UTES - Alternate letters [regularly found among] of gUmTrEeS.
17 Was anxious about colour of rear light (5)
CARED - CA (circa; about) RED (colour of red rear light).
21 Knight brought up in Bristol. (3)
SIR - Reverse hidden [brought up] in BRIStol.