Mistakenly call on Spooner’s receipt stash (6,4)

I believe the answer is:

pocket dial

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'spooner's receipt stash' is the definition.
I can't tell whether this defines the answer.

'mistakenly call on' is the wordplay.
'mistakenly' becomes 'pocket' (I can't justify this - if you can you should believe this answer much more).
'call' becomes 'dial' (I've seen this in another clue).
'on' means one lot of letters go next to another.
'pocket'+'dial'='POCKET DIAL'

Can you help me to learn more?

I've seen this clue in the Sydney Morning Herald.

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