I found this to be something of a mixture, some very easy and obvious clues and others where the wordplay was convoluted and difficult to parse. The result was that about 20% of the clues accounted for 75% of the solving time.
I have minor quibbles about the definition in 21ac and part of the wordplay in 17dn but apart from that there was nothing untoward (once I had managed to unravel the wordplay in a few clues).
Across
1 LITERACY T (model) in LIE (piece of fiction) RACY (provocative) – defn. scholarship (scholarly learning)
5 BECALM BE CALM (told to relax)
10 PARAGON PA (secretary) *(ORGAN)
11 INSTALL IN (popular) STALL (stand)
12 MANGA MAN (fellow) G[oes] A[bout] – a type of adult comic book popular in Japan
13 INTONATED TO in INNATE (natural) D (daughter)
14 HOVE INTO VIEW d&cd – according to Chambers and Collins the two equivalent terms are ‘come into view’ and ‘heave in sight’ so this would appear to be a mixture of a part of each. However, COED comes to the rescue with “heave in sight or into view”.
18 CONFECTIONER *(ENFORCE NOTIC[e])
21 CLOUD BASE CLOUD (blanket) BASE (support) – blanket and cloud are synonyms when used as a verb but the definition ‘low level cover’ is a little weak. Chambers defines ‘cloud base’ as “the undersurface of a cloud or clouds; the height of this above sea level”. COED gives “the level or altitude of the lowest part of a general mass of clouds”. As the undersurface of a cloud can be anything up to 60,000ft (18,000m) above sea level this could hardly be classed as low.
23 AMAZE A MAZE (a puzzle)
24 ETERNAL TER (territory) in LANE reversed (way back)
25 SHINDIG HINDI (foreign language) in S[trasbour]G
26 METIER *(TIME) ER (a royal)
27 ENCEINTE EN (measure) I (one) in CENT (money) E (note) – defn. ‘in the club’ (pregnant)
Down
1 LIPOMA PO (flower, river) in LIMA (South American city)
2 THRONE homophone of ‘thrown’ (was flustered) – john and throne are both informal terms for a lavatory
3 RIGMAROLE RIG (misrepresent) MA ROLE (mother’s character)
4 CONFIDENTIALLY I in CONFIDENT (assertive) ALLY (colleague)
6 EOSIN *(INSO[l]E)
7 ABATTOIR A BAT (a cricketer) TO IR (old government department, Inland Revenue)
8 MELTDOWN d&cd
9 LISTEN TO REASON *(INTOLERANT [b]O[s]SES)
15 OPERATIVE dd
16 ICE CREAM *(A RECCE I’M)
17 INDOLENT DOLE (welfare) in IN (popular) NT (book) – the New Testament is surely a collection of books rather than a single book. Both Chambers and COED define it as “the second part of the Bible”.
19 WARDEN *(Andrew) – one for our regular Guardian blogger!
20 LEAGUE dd
22 DENSE hidden in ‘garDEN SEtting’
Just got round to doing this……totally led astray in the SE corner by entering 28a as “slating”