Unstable structure had of course to be rebuilt with son (5,2,5)
I believe the answer is:
house of cards
'unstable structure' is the definition.
(I've seen this in another clue)
'had of course to be rebuilt with son' is the wordplay.
'to be rebuilt' indicates an anagram.
'with' indicates putting letters inside.
'son' becomes 's' (genealogical abbreviation for son).
'had'+'of'+'course'='hadofcourse'
'hadofcourse' is an anagram of 'houeofcards'.
'houeofcards' placed around 's' is 'HOUSE OF CARDS'.
(Other definitions for house of cards that I've seen before include "Unstable scheme" , "Flimsy structure" , "building that might fall over" .)