The facts are these: freewheeling stars will break apart defence (5,5)
I believe the answer is:
brass tacks
'the facts' is the definition.
(I have seen 'Hard facts' mean 'brass tacks' so perhaps 'facts' could also mean 'brass tacks')
'these freewheeling stars will break apart defence' is the wordplay.
'these freewheeling' is an anagram indicator (I've seen this in other clues).
'will break' is an insertion indicator (inserted letters break into the word).
'apart defence' becomes 'backs' (I can't explain this - if you can you should believe this answer much more).
'stars' is an anagram of 'rasst'.
'rasst' put into 'backs' is 'BRASS TACKS'.
'are' is the link.
Can you help me to learn more?
(Other definitions for brass tacks that I've seen before include "Nitty-gritty (got down to)" , "Hard facts" , "Basics" , "Basic realities (informal)" , "Details of practical business (colloq.)" .)