Across: 1 Homophone (reportedly) of ma’s turd (old lady’s stool) minus last letter (a bit short) = MASTER (teacher), 4 Secret (INnER) minus middle letter (essentially hidden) containing (imprisoning) middle letters (discovered) of lORDs = IN ORDER (lawful), 9 Commercial (AD) + undertaking (MISSION) = ADMISSION (entrance), 10 Alternate letters (regularly) of wItNeSsEs + 1st letter (a bit) of Trouble = INSET (figure in the corner), 11 Whimsical reading of UPSET = disturb as groups of people (SET) with UP (on horseback), 12 1st letters (characters facing) Extreme Neuropathic Tremors follow (join) queue (STRING) = STRINGENT, 13 ENGland + ARE (from the clue) containing (assuming) Germany (D) = (will provide) EN GARDE (challenge for defence), 15 Alternate letters (at intervals) of aDvErT containing (claiming) reversal (backing) of solid (SET) = DETEST (can’t stand), 17 Fish from Loire (POISsON) minus (not) (s)pecial = POISON (venomous), 19 Payment terms (COD) contained in document (DEED) = DECODED (figured out), 22 makeOVER TO NESting hides (boxes) the answer = OVERTONES (they suggest), 24 French team EQUIPe truncated (the majority of) = EQUIP (supply), 26 Homophone (to the audience) of look (peek) = PIQUE (ill-feeling), 27 Press (IRON) with poem (ODE)  containing (writing about) team (XI)  = IRON OXIDE (that’s rusty), 28 REFEREeS anagrammed (devastated) minus one e (losing energy) = REEFERS (joints), 29 2nd letters (each second) of sEptember’s fFestiniog + FETE (show) = EFFETE (decadent). 

Down: 1 This composer (ME) + imitating (AS) + ultravox front man (URE) = MEASURE (assess), 2 Dismisses (StUMPS in the cricketing sense) minus (lost) (T)ime = SUMPS (reservoirs), 3 Anagram (developed) of MASTERY inside (among) last letters (finally) of financE brokerS = EASY TERMS (funding scheme), 4 Anagram (flying) of DRONE follows (under) outer letters (edges) of IceberG = IGNORED (disregarded), 5 Operating (ON) + one (I) + leg (ON) = ONION (it makes you weep), 6 Showed contempt (DISSED) + for each (PER) inserted (bottled) = DISPERSED (spread), 7 Eggs (ROE) inserted (put) into rubbish (TAT)? No, the other way round = ROTATE (turn), 8 The answer, TISSUE (material), comes from (developed by) 1st letters (originally) the words 4-9., 14 GO + REQUEST anagrammed (to become) = GROTESQUE (outlandish), 16 DD with TICKED OFF meaning angry in US, 18 Grandmother (NAN) + deNIES minus de (dismissing the first two) = NANNIES (nurses), 19 Anagram (about) of POSTED = DESPOT (abusive leader), 20 Quietly (P) inserted into (disconnecting sections, ie the DE from the LETE) key (DELETE) = DEPLETE (drain), 21 Dbe (perhaps) of air ambulance (ChOPPER) minus (is leaving) (h)hospital = COPPER (policeman), 23 Answer is hidden (to some extent) in whaT HE MEans = THEME (a recurrent idea), 25 College (UNI) + TheatrE minus middle letters (when exhausted) = UNITE (act together).