Turning points for a number in a new post (6)
I believe the answer is:
pivots
'turning points' is the definition.
(a pivot is the point around which something turns)
'a number in a new post' is the wordplay.
'a number' becomes 'iv' (IV is an example**).
'in' is an insertion indicator.
'a new' is an anagram indicator.
'post' with letters rearranged gives 'pots'.
'iv' inserted within 'pots' is 'PIVOTS'.
'for' acts as a link.
(Other definitions for pivots that I've seen before include "Swivels" , "Rotates" .)