Team is back on Derbyshire's boundaries (4)
I believe the answer is:
side
'team' is the definition.
(both can mean a sports team)
'is back on derbyshire's boundaries' is the wordplay.
'back' is a reversal indicator.
'on' says to put letters next to each other.
'boundaries' says to hollow out the word (remove centre letters) (only the edge or boundary letters remain).
'derbyshire' with its middle taken out is 'de'.
'is' written backwards gives 'si'.
'si'+'de'='SIDE'
(Other definitions for side that I've seen before include "Lateral team" , "Pomposity - bias - team" , "Minor" , "Airs and graces" , "Neighbourhood" .)