Still the old temperature (3)
I believe the answer is:
yet
'still' is the definition.
(yet can mean still or so far)
'the old temperature' is the wordplay.
'the old' becomes 'ye' (resembles a historical spelling of 'the').
'temperature' becomes 't' (abbreviation).
'ye'+'t'='YET'
(Other definitions for yet that I've seen before include "Still, so far" , "Though; still" , "Thus far" , "Up to the present time" , "in spite of that" .)