He or I, perhaps working close by, calm him (8,6)

I believe the answer is:

chemical symbol

'he or i perhaps' is the definition.
(He and I are the symbols for helium and iodine)

'working close by calm him' is the wordplay.
'working' is an anagram indicator.
'close'+'by'+'calm'+'him'='closebycalmhim'
'closebycalmhim' with letters rearranged gives 'CHEMICAL SYMBOL'.

I've seen this clue in The Times.

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