A certain period in the use of a timer (7)

I believe the answer is:

interim

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'a certain period' is the definition.
'interim' can be an answer for 'period' (interim is a kind of period). I'm not certain of the 'a certain' bit.

'in the use of a timer' is the wordplay.
'the use of' indicates an anagram.
'timer' with letters rearranged gives 'terim'.
'in'+'terim'='INTERIM'

Can you help me to learn more?

(Other definitions for interim that I've seen before include "Caretaker" , "Stopgap" , "Temporary - provisional" , "Meantime - provisional" , "temporary period" .)

I've seen this clue in the Evening Standard.

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