Only fish in bottom of oven (4)
I believe the answer is:
sole
This clue is a triple definition!
'only' is the first definition.
(I know that only can be written as sole)
'fish' is the second definition.
(sole is a kind of fish)
'in' is a link.
'bottom of oven' is the third definition.
'sole' can be an answer for 'bottom' (sole is a kind of bottom). I am not sure about the 'of oven' bit.
Can you help me to learn more?
(Other definitions for sole that I've seen before include "fish > that's never less than foot in length" , "Kind of fish - lose it" , "A lone sort of fish - lose it" , "A lone flat fish?" , "Exclusive class of fish" .)