Use it to apprehend fences of narcotics? (5)
I believe the answer is:
sense
'apprehend fences of narcotics?' is the definition.
'sense' can be an answer for 'apprehend' (thesaurus). I am not certain of the 'fences of narcotics?' bit.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for sense that I've seen before include "Get an impression" , "smell, for example" , "Sat lazily; hung loosely" , "Could be common or horse" , "Feeling - reason" .)