Concealing the old crack was responsible for the disaster (7)
I believe the answer is:
tragedy
'the disaster' is the definition.
(synonyms)
'concealing the old crack' is the wordplay.
'concealing' means one lot of letters goes inside another.
'the old' becomes 'aged' (I've seen this before).
'crack' becomes 'try' (I've seen this in another clue).
'aged' placed within 'try' is 'TRAGEDY'.
'was responsible for' acts as a link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for tragedy that I've seen before include "Such a story ends unhappily" , "Dire misfortune" , "King Lear, perhaps" , "Drama genre" , "Distressing event" .)