It's dismally dull, back in the outskirts of Derby (6)
I believe the answer is:
dreary
'it's dismally dull' is the definition.
I can't tell whether this definition defines the answer.
'back in the outskirts of derby' is the wordplay.
'back' becomes 'rear' (something's rear is its back).
'in the' is an insertion indicator.
'outskirts of' says to hollow out the word (remove centre letters).
'derby' with its middle removed is 'dy'.
'rear' put inside 'dy' is 'DREARY'.
Can you help me to learn more?
(Other definitions for dreary that I've seen before include "Grey and dull" , "Dark" , "Dismal, funeral" , "Depressingly dull" , "Overcast" .)