Solution to 17D has been deliberately left unsolved and is to be answered only by a non-regular / novice commenter, with proper annotation. Those who have answered earlier in the week, please give others a chance.
Open for anyone to solve, if not solved by 1 PM.
ACROSS
1 It might bring rain near Indian military base until summer, primarily (6) NIMBUS Acrostic
4 One's permitted to fabricate new watch without crown to begin with (8) LICENSEE {LIE}{N}{SEE} over {Cr..n}
9 Community hospital adjoining city (6) PARISH {H}<=>{PARIS}
10 Shopkeeper aspired to tour Roman Catholic Church at last (8) MERCHANT {ME{RC}{c...cH}ANT}
12 Player from Spain excitedly accompanying them for the most part (8) THESPIAN {SPAIN}*<=>{THEm}
13 Recovery of posh platinum vase (6) UPTURN {U}{PT}{URN}
15 A lot of smart newlyweds having sex in lounges (7,5) SITTING ROOMS {STINg}{GROOMS} over {IT}
18 On vacation, healthy chaps rebuilding local hotel compound (5,7) ETHYL ALCOHOL {He...hY} in {LOCAL+HOTEL}*
21 Setter starts to disclose information to company doctor (6) MEDICO {ME}{Di...e}{In...n}{CO}
22 Rerelease unclear changes before end of Month (8) RELAUNCH {UNCLEAR}*{m..tH}
24 Flying from Austria through South Africa, say, avoiding borders of Namibia (8) AVIATION {A}{VIA}{naTION}
25 Element of hydrogen extracted from compound of helium and iodine (6) MILIEU {hELIUM+I}*
26 Italian soldier wearing dirty pants in tension (8) RIGIDITY {R{I}{GI}DITY*}
27 Dirty husband backing recurrent violations without a bit of embarrassment (6) SMIRCH {H}<=>{CRIMeS<=}
DOWN
1 Retired employees retaining position at work and jobs for the boys (8) NEPOTISM {M{SIT}{OP}EN}<=
3 Innocent lives overwhelmed by pathetic sound, perhaps (15) UNSOPHISTICATED {IS} in {PATHETIC+SOUND}*
5 Suggestion - avoid eating sandwiches (4) IDEA [T]
6 President ultimately dismissed active impeachment cases? That's a defence strategy (6,9) ESCAPE MECHANISM {IMPEACHMENt+CASES}*
7 Excellent pals? (4-2) SLAP-UP [PALS}* [RA] (Correction - PALS<= )
8 Remaining measuring instrument needs a little servicing (6) EXTANT sEXTANT
11 Planet inhabited by colourful spotted cats (7) MARGAYS {MAR{GAY}S}
17 Lecturer abruptly concluded after a while (8) ?L?H?U?H (Addendum - ALTHOUGH {L}{THOUGHt}<=>{A} - See comments)
19 Reduce troublemaker's voice (6) IMPAIR {IMP}{AIR}
20 Moving slowly, say, transporting diamonds to current capital of Germany (6) EDGING {E{D}G}{IN}{Ge...y}
23 Pack fish after removing head (4) ROUT tROUT
Reference List
New = N, Hospital = H, Roman Catholic = RC, Posh = U, Sex = IT, Austria = A, Italian = I, Soldier = GI, Husband = H, Check = CH, Lecturer = L, Diamonds = D
