Across
1 Across Parasitic infection from disturbed Irish tonics (11) → TRICHINOSIS Anagram
Anagram of “IRISH TONICS”.
8 Across Idle hours found in Hawaiian lei surely (7) → LEISURE Hidden word
Hidden inside “lei surely”.
9 Across Leaders of awkward uncles never trust youngsters, parent's sister (5) → AUNTY Initialism
First letters of: awkward, uncles, never, trust, youngsters.
10 Across Bounces holding a thousand, explosive devices (5) → BOMBS Container
M inside BOBS.
11 Across A skin disease found in a julep rosy (7) → LEPROSY Hidden word
Hidden inside “julep rosy”.
12 Across Sweetheart's satellite, a getaway after marriage (9) → HONEYMOON Charade
HONEY + MOON.
15 Across Increase suddenly, as seen backwards in fans' input oohs (5,2) → SHOOT UP Hidden backwards
Hidden backwards inside “input oohs”.
16 Across Go away, as leaders of local elephants always visit England (5) → LEAVE Initialism
First letters of: local, elephants, always, visit, England.
18 Across Go roam map alternately for mum's dad (5) → GRAMP Alternate letters
Every other letter of “go roam map”, starting with the first.
19 Across Vacation, oh daily reshuffled (7) → HOLIDAY Anagram
Anagram of “OH DAILY”.
20 Across Buffet, or an eclectic medley (11) → SMORGASBORD Double definition
Two separate definitions of the same word.
Down
1 Down Bag and kilt scrambled to boast (4,3) → TALK BIG Anagram
Anagram of “BAG KILT”.
2 Down Expression, cores of dig, ode, fig, son, camel (5) → IDIOM Middle letters
Middle letters of: dig, ode, fig, son, camel.
3 Down Catches found in an aloha Ulster celebration (5) → HAULS Hidden word
Hidden inside “aloha Ulster”.
4 Down No, in Scots, from barcode standard turned around (3) → NAE Reversal
EAN reversed.
5 Down Hair wash made from fake mess (7) → SHAMPOO Charade
SHAM + POO.
6 Down Blazing orb followed by low spirits, at dusk (7) → SUNDOWN Charade
SUN + DOWN.
7 Down Fronts of deer running yearly, leaping yonder, spoken with no emotion (5) → DRYLY Initialism
First letters of: deer, running, yearly, leaping, yonder.
11 Down Chiefly, lazy artists yell using paint, for an easy basketball shot (5) → LAYUP Initialism
First letters of: lazy, artists, yell, using, paint.
12 Down Curved fastener followed by cries of delight are smoking pipes (7) → HOOKAHS Charade
HOOK + AHS.
13 Down Incapable, put onto scrambled (3,2,2) → NOT UP TO Anagram
Anagram of “PUT ONTO”.
14 Down Epee and DIY scrambled, utterly drunk (3,4) → PIE EYED Anagram
Anagram of “EPEE DIY”.
15 Down Short signature followed by a master's degree, a Greek letter (5) → SIGMA Charade
SIG + MA.
16 Down Rearranged, still swings rhythmically (5) → LILTS Anagram
Anagram of “STILL”.
17 Down Sound-related Australian currency with computer input/output (5) → AUDIO Charade
AUD + IO.
19 Down Go, then an hour, reversed, to monopolize (3) → HOG Reversal
GO H reversed.
