Temperature on oven grill (5)
I believe the answer is:
toast
'grill' is the definition.
(thesaurus)
'temperature on oven' is the wordplay.
'temperature' becomes 't' (abbreviation).
'on' means one lot of letters go next to another.
'oven' becomes 'oast' (oast is a kind of oven).
't'+'oast'='TOAST'
(Other definitions for toast that I've seen before include "Drink to the healt of" , "Raising of glasses" , "Brown in front of a fire" , "Formally drink a health" , "meal component" .)