Spirited detectives taking several back (7)
I believe the answer is:
dynamic
'spirited' is the definition.
(I've seen this in another clue)
'detectives taking several back' is the wordplay.
'detectives' becomes 'CID' (abbreviation for Criminal Investigation Department).
'taking' is an insertion indicator.
'several' becomes 'many' (I've seen this in another clue).
'back' is a reversal indicator.
'cid' enclosing 'many' is 'cimanyd'.
'cimanyd' back-to-front is 'DYNAMIC'.
(Other definitions for dynamic that I've seen before include "Constantly changing" , "I'm Candy (anag) - full of beans" , "Powerful and vigorous" , "High-powered" , "Driving" .)