Crazy grandma consumed by degrees (7)
I believe the answer is:
bananas
'crazy' is the definition.
(thesaurus)
'grandma consumed by degrees' is the wordplay.
'grandma' becomes 'nana' (I've seen this before).
'consumed by' means one lot of letters goes inside another.
'degrees' becomes 'bas' (BA is an example).
'nana' going into 'bas' is 'BANANAS'.
(Other definitions for bananas that I've seen before include "bats" , "off 27 [TROLLEY]" , "hands" , "Fruit - nuts" , "Crazed" .)