US lawman that is caught with electronic listening device (8)
I believe the answer is:
earpiece
'listening device' is the definition.
'earpiece' can be an answer for 'device' (earpiece is a kind of device). I am unsure of the 'listening' bit.
'us lawman that is caught with electronic' is the wordplay.
'us lawman' becomes 'earp' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'that is' becomes 'ie' (abbreviation for id est, 'that is' in Latin).
'caught' becomes 'c' (cricket abbreviation).
'with' means one lot of letters go next to another.
'electronic' becomes 'e' (as in e-mail or e-books).
'earp'+'ie'+'c'+'e'='EARPIECE'
Can you help me to learn more?
(Other definitions for earpiece that I've seen before include "Headset part" , "What lets you hear communications" , "for audibility" , "box?" , "receiver" .)