Letter to a police inspector from a pickpocket (3)
I believe the answer is:
dip
'pickpocket' is the definition.
(synonyms)
'letter to a police inspector from a' is the wordplay.
I cannot quite see how this works, but
'letter' could be 'p' and 'p' is found within the answer.
'inspector' could be 'di' (abbreviation for Detective Inspector) and 'di' is present in the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for dip that I've seen before include "Dunk" , "See 21" , "Sink; thick sauce" , "A brief informal swim" , "An informal swim or a downward slope" .)