Criminal out by alarm capable of being altered (10)

I believe the answer is:

ambulatory

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'capable of being altered' is the definition.
I can't tell whether this definition defines the answer.

'criminal out by alarm' is the wordplay.
'criminal' is an anagram indicator.
'out'+'by'+'alarm'='outbyalarm'
'outbyalarm' with letters rearranged gives 'AMBULATORY'.

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