Worker traps extremely gullible negotiator (5)
I believe the answer is:
agent
'negotiator' is the definition.
(agent is a kind of negotiator)
'worker traps extremely gullible' is the wordplay.
'worker' becomes 'ant' (worker is a type of ant).
'traps' means one lot of letters goes inside another.
'extremely' means to remove the middle letters (only the extremes of the word are used).
'gullible' with its centre removed is 'ge'.
'ant' placed around 'ge' is 'AGENT'.
(Other definitions for agent that I've seen before include "that may be secret?" , "One may be working" , "One representing others" , "Representative - means" , "Actors' manager" .)