A pleasant solve from Kite . . .
. . . with an unpleasant theme of viruses

| ACROSS | ||
| 9 | INFLUENZA |
Local pipe filling area that harbours unknown illness (9)
|
| {FLUE (pipe) inside (filling) INN (local) + A (area)} around (harbours) Z (unknown) | ||
| 10 | TSARS |
Rulers having temperature and respiratory problem (5)
|
| T (temperature) + SARS (respiratory problem) | ||
| 11 | RHINO |
Discover catarrh in omnivorous beast (5)
|
| Hidden in (discover) [CATAR]RH IN O[MNIVOROUS] | ||
| 12 | HEPATITIS |
Cook briefly ate this pie leading to liver problem (9)
|
| Anagram of (cook) {AT[E] minus last letter (briefly) + THIS + PIE} | ||
| 13 | ANGORAS |
Cats old, endlessly irritated, so hiding (7)
|
| O (old) inside (hiding) {ANGR[Y] (irritated) minus last letter (endlessly) + AS (so)} | ||
| 14 | APPROVE |
Permit pages to ramble after start of address (7)
|
| First letter of (start of) A[DDRESS] + {P + P} (pages) + ROVE (ramble) | ||
| 17 | PHAGE |
Bug is hard inside leaf (5)
|
| H (hard) inside PAGE (leaf) | ||
| 19 | DUE |
Expected nobleman, not king (3)
|
| DU[K]E (nobleman) minus (not) K (king) | ||
| 20 | RETRO |
Old-fashioned, half-hearted rotter disgruntled (5)
|
| Anagram of (disgruntled) ROT[T]ER minus a central letter T (half-hearted) | ||
| 21 | ELAPSES |
Pleases criminal making passes (7)
|
| Anagram of (criminal) PLEASES | ||
| 22 | ROUGHLY |
Approximately like a frill, say (7)
|
| Homophone of (say) RUFFLY (like a frill) | ||
| 24 | NOROVIRUS |
Survivor on back, ignoring a very nasty cause of stomach upset (9)
|
| {SUR[V]IVOR + ON} reversed (back) minus (ignoring) one V (a very) | ||
| 26 | UGRIC |
Type of acid preserving starter of Galloway tongue (5)
|
| URIC (type of acid) around (preserving) first letter of (starter of) G[ALLOWAY] | ||
| 28 | EBOLA |
Sample of placebo lacks noxious agent (5)
|
| Hidden in (sample of) [PLAC]EBO LA[CKS] | ||
| 29 | BOMBSHELL |
Blonde type providing unwelcome news (9)
|
| Double definition | ||
| DOWN | ||
| 1 | PIER |
Reportedly like quay (4)
|
| Homophone of (reportedly) PEER (like) | ||
| 2 | OFFING |
Part of the sea raising, ignoring depth (6)
|
| [D]OFFING (raising) minus (ignoring) D (depth) | ||
| 3 | HUMOURLESS |
“Our slum” – he’s funny or maybe not (10)
|
| Anagram of (funny) {OUR SLUM HE’S}, i.e., maybe not funny | ||
| 4 | INCHES |
Creeps offering headless birds (6)
|
| [F]INCHES (birds) minus first letter (headless) | ||
| 5 | WARPLANE |
How to produce elan in Lancaster perhaps (8)
|
| Reverse anagram of (how to produce) WARP LANE = ELAN, referring to a heavy bomber of WWII | ||
| 6 | STET |
Son drops off hat to remove alteration (4)
|
| STET[SON] (hat) minus (drops off) SON | ||
| 7 | LAST POST |
Ending deliveries, it indicates time to retire (4,4)
|
| Double definition | ||
| 8 | ISIS |
Terrorists‘ disaster – lack of credit (4)
|
| [CR]ISIS (disaster) minus (lack of) CR. (credit) | ||
| 13 | AMPLE |
Large crown of tree’s falling down (5)
|
| MAPLE (tree) with first letter moving down a space (crown [is] falling down) | ||
| 15 | PORTUGUESE |
Western Republicans have guts with Europe revolting (10)
|
| Anagram of (revolting) {GUTS + EUROPE} | ||
| 16 | EBONY |
Black kite’s tail thin (5)
|
| Last letter of (tail [of]) [KIT]E + BONY (thin) | ||
| 18 | A FAIR COP |
Admission of wrongdoing by American blonde (Bobby) (1,4,3)
|
| A (American) + FAIR (blonde) + COP (bobby) | ||
| 19 | DESCRIBE |
Report of French author (8)
|
| DE (of [in] French) + SCRIBE (author) | ||
| 22 | RESUME |
Continue sketch (6)
|
| Double definition | ||
| 23 | HERPES |
Woman’s exercise leading to systemic disease (6)
|
| HER (woman’s) + PE (exercise) + first letter of (leading to) S[YSTEMIC] | ||
| 24 | NEED |
Originally called daughter or miss (4)
|
| NÉE (originally called) + D (daughter) | ||
| 25 | VIAL |
Delivered low container (4)
|
| Homophone of (delivered) VILE (low) | ||
| 27 | COLD |
Unfriendly characters in Poland locked up (4)
|
| Hidden in (characters in) [POLAN]D LOC[KED] inverted (up) | ||