Agreed it isn't about to fall apart! (12)
I believe the answer is:
disintegrate
'fall apart' is the definition.
(I've seen this before)
'agreed it isn't about' is the wordplay.
'about' indicates anagramming the letters.
'agreed'+'it'+'isnt'='agreeditisnt'
'agreeditisnt' with letters rearranged gives 'DISINTEGRATE'.
'to' is the link.
(Other definitions for disintegrate that I've seen before include "Decompose" , "Lose all cohesion" , "decay" , "Shatter" , "Crumble" .)