What you've been cooking since getting into a rut? (6)
I believe the answer is:
ragout
'what you've been cooking' is the definition.
I can't judge whether this definition defines the answer.
'since getting into a rut?' is the wordplay.
'since' becomes 'ago' (I've seen this before).
'getting into' indicates putting letters inside.
'ago' inserted within 'rut' is 'RAGOUT'.
Can you help me to learn more?
(Other definitions for ragout that I've seen before include "Temper showing? No, it's a stew" , "Spicy dish" , "Seasoned stew of meat and vegetables" , "Seasoned dish of stewed meat and vegetables" , "Stew of meat and veg" .)