Surly detective taking over (6)
I believe the answer is:
morose
'surly' is the definition.
(thesaurus)
'detective taking over' is the wordplay.
'detective' becomes 'morse' (I've seen this before).
'taking' means one lot of letters goes inside another.
'over' becomes 'o' (cricket abbreviation).
'morse' placed around 'o' is 'MOROSE'.
(Other definitions for morose that I've seen before include "Lugubrious" , "Sullen and ill-tempered" , "Miserable" , "dark" , "Sullen and moody" .)