No 12278, Friday 30 Mar 2018, Arden

Today being Friday only the blank clues will be posted. All those who are silent followers of the blog are requested to post answers with annotations in the comments section. In your own interest please avoid looking up the answers from the interactive version. Don't hesitate to post your annotations, in case you make a mistake someone will correct it with the right annotation.

Please note a change. Each commenter is requested to post only 5 answers till 1 PM thereby giving others also a chance to participate. Between 1 PM and 4 PM more answers may be posted in case any are remaining to be answered.

The regular blog will replace the clues at 4 PM after which anyone is free to comment. 

Thanks everyone for the response. Here is the regular blog

ACROSS
1   He may tell the referee (7-6) WHISTLE-BLOWER [C&DD]
10 Reading about allowing bill to pass — it's all gas (5) RADON {R}{AD}{ON}
11 Can I act it out as a strategist? (9) TACTICIAN*
12 It's hard thing to mutate a man's gene (9) MANGANESE*
13 Difficult time without right joint (5) MITRE {MIT{R}E*}

Public Domain, Link

14 Reference books have no sign of enunciation (7) DICTION DICTIONaries
16 Perhaps the bug has swallowed a drop of poison, check (7) INSPECT {INS{Po...n}ECT}
18 Openness, resolve and courage, are timeless (7) CANDOUR {AND+COURage}*
20 Sea creature had hair all over (7) MANATEE {MAN{ATE}E}

By U.S. Department of the Interior, U.S. Geological Survey - Photo from U.S. Geological Fact Sheet 010-99; FS-010-99, Public Domain, Link

22 About to mediate — yes, no fighting (5) TRUCE {TRU{C}E}
24 Bitter shock, almost breaks down (9) ANGOSTURA {ANGO{STUn}RA}

By Didier Descouens - Own work, CC BY-SA 3.0, Link

26 Material to be kept in pub party is set up (5,4) OLIVE DRAB {LIVE} in {BAR|{DO}<=
27 Stand to lose your head, Kolinsky! (5) EASEL wEASEL
28 This time, cards are different for festive season (13) CHRISTMASTIDE*

DOWN
2   Man's nice at heart, without dress, devoted to pleasure (7) HEDONIC {HE}{DON|}{nICe}
3   Crazy Romans in a principality (3,6) SAN MARINO*

4   Turner's husband brought in dead (5) LATHE {LAT{H}E}
5   Germ in cream, but I use (9) BACTERIUM*
6   Drug rise becomes imperious (5) OPIUM IMPeriOUs* [CA]
7   I slept off after the last missive (7) EPISTLE {thE}{I+SLEPT}*
8   Drugs given before surgery — intent is to send Charlie for initial test (13) PREMEDICATION PREMEDI(-t+c)CATION
9   Halt debenture, refuse in a clandestine manner (5-3-5) UNDER-THE-TABLE*

15 Deserter from country living in sewers (6,3) NORWAY RAT {NORWAY} {RAT}

By AnemoneProjectors (talk) - Brown Rat (Rattus norvegicus) Uploaded by Snowmanradio, CC BY-SA 2.0, Link

17 Growing old, making sense of change (9) SENESCENT {SENSE*}{CENT}
19 Sustain sharpness, flip the top (7) NOURISH (-s+n)NOURISH
21 Bound to use dusters (7) TRUSSED*
23 Some time left to bring up the gum (5) ELEMI [T<=]
25 Leading girl of the band at a sporting venue (5) GABBA {Girl}{ABBA}

GRID