Place trap underground with modern technology (8)
I believe the answer is:
internet
'modern technology' is the definition.
'place trap' is the wordplay.
'place' becomes 'inter' (I can't explain this - if you can you should give a lot more credence to this answer).
'trap' becomes 'net' (net is a kind of trap).
'inter'+'net'='INTERNET'
'underground with' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
(Other definitions for internet that I've seen before include "Global computer communications network" , "surfing place" , "The computer web" , "go surfing here?" , "World computer network" .)