Tracks ignored in Derry, poor condition causing this? (10)

I believe the answer is:

derailment

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'this?' is the definition.
The definition suggests a singular noun which matches the answer.

'tracks ignored in derry poor condition' is the wordplay.
'tracks' becomes 'ry' (abbreviation for railway).
'ignored in' suggests deleting specific letters.
'poor condition' becomes 'ailment' (someone with an ailment is poorly).
'derry' with 'ry' taken out is 'der'.
'der'+'ailment'='DERAILMENT'

'causing' is the link.

Can you help me to learn more?

(Another definition for derailment that I've seen is " Train accident".)

I've seen this clue in The Telegraph.

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