Catch the part that breaks (4)
I believe the answer is:
trap
'catch' is the definition.
(I know that trap is a type of catch)
'part that breaks' is the wordplay.
'that breaks' indicates an anagram.
'part' is an anagram of 'TRAP'.
'the' acts as a link.
(Other definitions for trap that I've seen before include "Means of transport - sometimes sprung!" , "Part of a snare" , "Means of transport (sometime sprung!)" , "Light carriage; ensnare" , "Lock" .)