Left a number at the gate (6)
I believe the answer is:
portal
'the gate' is the definition.
(I've seen this in another clue)
'left a number' is the wordplay.
'left' becomes 'port' (left side of a ship - opposite of starboard).
'number' becomes 'l' (L is an example).
'port'+'a'+'l'='PORTAL'
'at' is the link.
(Other definitions for portal that I've seen before include "Grand sort of entrance." , "An imposing door or gate" , "An imposing gate or doorway" , "Gate, entrance" , "'Doorway, entrance (6)'" .)