Normal temperature proportion (4)

I believe the answer is:

part

'proportion' is the definition.
(thesaurus)

'normal temperature' is the wordplay.
'normal' becomes 'par'.
'temperature' becomes 't' (abbreviation).
'par'+'t'='PART'

(Other definitions for part that I've seen before include "Portion of a whole" , "goodbye" , "Region" , "Section of a whole" , "Some; break" .)

I've seen this clue in The Independent.

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