Reading novel about non-starter that's threatened (2,6)

'threatened' is the definition.
(I've seen this in another clue)

'reading novel about non-starter' is the wordplay.
'novel' is an anagram indicator (letters in a new or novel order).
'about' indicates putting letters inside.
'starter' says to take the initial letters.
The initial letter of 'non' is 'n'.
'reading' anagrammed gives 'indager'.
'indager' enclosing 'n' is 'IN DANGER'.

'that's' is the link.