If it's broken, that's understandable (4)

I believe the answer is:

code

I'm a little stuck... Click here to teach me more about this clue!

'broken that's understandable' is the definition.
I can't tell whether this defines the answer.

'if it's' is the wordplay.
'if' becomes 'cod' (I am not sure about this - if you are sure you should believe this answer much more).
'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" .)

I've seen this clue in the Evening Standard.

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