Man left nametag around entrance (4)
I believe the answer is:
gate
'entrance' is the definition.
(type of entrance)
'man left nametag around' is the wordplay.
'left' indicates named letters should be taken away.
'around' is a reversal indicator.
'nametag' with 'man' removed is 'etag'.
'etag' written backwards gives 'GATE'.
(Other definitions for gate that I've seen before include "Airport boarding point" , "Movable opening" , "It may be barred" , "Confine to college" , "Narrow opening" .)