Gambling town discovered in venture north (4)
I believe the answer is:
reno
'gambling town' is the definition.
(I've seen this in another clue)
'discovered in venture north' is the wordplay.
'discovered' says the answer is hidden in the clue (remove the letters covering the answer in the clue).
'RENO' is hidden in the letters of 'in venture north'.
(Other definitions for reno that I've seen before include "gambling centre" , "US gambling resort" , "Nevada city of Nero" , "City in Nevada known for gambling and easy marriage/divorce" , "City in Nevada known for casinos and easy divorce" .)