Detectives finding drug during leave worry (8)
I believe the answer is:
disquiet
'worry' is the definition.
(thesaurus)
'detectives finding drug during leave' is the wordplay.
'detectives' becomes 'dis' (Detective Inspectors, DIs).
'finding' says to put letters next to each other.
'drug' becomes 'e' (e is another name for ecstasy).
'during' is an insertion indicator.
'leave' becomes 'quit' (quitting is a kind of leaving**).
'e' inserted inside 'quit' is 'quiet'.
'dis'+'quiet'='DISQUIET'
(Other definitions for disquiet that I've seen before include "Fear" , "concern" , "Feeling of unease" , "Vague unease, anxiety" , "Restlessness" .)