If it's broken, that's understandable (4)
I believe the answer is:
code
'broken that's understandable' is the definition.
I can't judge whether this defines the answer.
'if it's' is the wordplay.
'if' becomes 'cod' (I can't justify this - if you can you should give a lot more credence to this answer).
'it' becomes 'e' ('e' can mean 'electronic' which is similar to 'IT').
'cod'+'e'='CODE'
Can you help me to learn more?
(Other definitions for code that I've seen before include "Cryptographic system" , "Collection of laws" , "Computing instructions" , "Established standards" , "System of rules" .)