Low criminal very slow trailing detectives (12)
I believe the answer is:
'low' is the definition.
(I've seen this before)
'criminal very slow trailing detectives' is the wordplay.
'criminal very' becomes 'conso' (I can't explain this - if you can you should give a lot more credence to this answer).
'slow' becomes 'late' (I've seen this in other clues).
'trailing' is a charade indicator (letters next to each other).
'detectives' becomes 'dis' (Detective Inspectors, DIs).
'consolate' put after 'dis' is 'DISCONSOLATE'.
Can you help me to learn more?
(Other definitions for disconsolate that I've seen before include "Unhappy and unable to be comforted" , "Deeply sad" , "Woebegone" , "Unhappy and impossible to comfort" , "Sad; beyond comfort" .)