Waffle's fallen apart over back of pan (7)
I believe the answer is:
flannel
'waffle's' is the definition.
(thesaurus)
'fallen apart over back of pan' is the wordplay.
'apart' indicates an anagram.
'over' indicates putting letters inside.
'back of' says to take the final letters.
The final letter of 'pan' is 'n'.
'fallen' anagrammed gives 'flanel'.
'flanel' going around 'n' is 'FLANNEL'.
(Other definitions for flannel that I've seen before include "hedge" , "it comes in handy for washing" , "Cloth used to wash the face and body" , "Light fabric" , "One way to rub clean" .)