Across
4a
(and 4 Across) Doctor vents one lung - making news programme's introduction showing individuals that require a helping hand? (5,7)
See 1 Across
American city hotel putting Yoko and, reportedly, John Lennon up initially (8)
Peter Parker ultimately being more cautious (5)
Tyrant's 'psychic powers' inspired by E - according to coded dispatch (6)
100 not entirely competent people backing one that can climb to the top? (5,3)
Garden in East End requires work (4)
Recreation in New Orleans with taxi seconds away (10)
Microsoft product, Excel finally breaks - another is pointless for China, say (5,5)
Possessing heroin - after comedian... (4)
...mostly performs at clubs potentially developing habit? (8)
Funny ending to Freddie Starr's book (6)
Bishop discovered card game on vacation - perhaps pontoon (5)
Dancer maybe receiving marks - wanting third judge's conclusion to be prompt (8)
27a
(and 27 Across) So angry about agent coming back with terms for another Harry Potter (7,5)
See 26 Across
Down
On the contrary, some lemon grass gives a little garden whimsy? (5)
They make cubes - but nothing's squared? (3)
Quorate assembly reaches halfway point? (7)
Discourage injured Rooney dropping back at World Cup (4,4,5,2)
There will be correspondence in this paper principally over street fight (7)
Arranged lower fee if taking time to deliver more than 7,000 tonnes of iron (6,5)
Wide-ranging knowledge supported by computer's data retrieval (6-3)
Writing a year off after regularly consulting ballot box (7,4)
Provide disc to correct software problem without lead for laptop - if it crashes it could be disastrous (9)
Universal ID traps down-and-outs (7)
Design plug-in memory device on a phone, originally (4,3)
Grubby, like a pomegranate ... (5)
... and not mandarin orange segment (3)
Type letters or click words in the clue