Rail caught, breaking my new tool (9)

I believe the answer is:

corncrake

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'rail' is the definition.
(corncrake is a kind of rail)

'my new tool' is the wordplay.
'my' becomes 'cor' (both are expressions of surprise).
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'tool' becomes 'crake' (I can't justify this - if you can you should believe this answer much more).
'cor'+'n'+'crake'='CORNCRAKE'

'caught breaking' is the 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 corncrake that I've seen before include "kind of rail" , "Bird" .)

I've seen this clue in The Independent.

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