Try second cigarette up north (4)
I believe the answer is:
stab
'try' is the definition.
(I know that stab is a type of try)
'second cigarette up north' is the wordplay.
'second' becomes 's' (common abbreviation).
'cigarette up' becomes 'bat' (I can't justify this - if you can you should believe this answer much more).
'north' says the letters should be written in reverse (in a down clue, letters go up or 'northward').
'bat' backwards is 'tab'.
's'+'tab'='STAB'
Can you help me to learn more?
(Other definitions for stab that I've seen before include "Attack with a knife" , "Thrust (weapon into)" , "Inflict wound with knife" , "Try - skewer" , "Run through - essay" .)