Purpose of oven door (3)
I believe the answer is:
end
'purpose' is the definition.
(I've seen this before)
'of oven door' is the wordplay.
'of' indicates a hidden word.
'END' is hidden within 'oven door'.
(Other definitions for end that I've seen before include "Conclusion, finish" , "Aim - point - finish" , "scrap" , "Intention" , "Game at bowls" .)