Second option is coffee with last of sugar (6)
I believe the answer is:
latter
'second option' is the definition.
(the second or latter of two options)
'coffee with last of sugar' is the wordplay.
'coffee' becomes 'latte' (I've seen this in other clues).
'with' says to put letters next to each other.
'last of' indicates one should take the final letters.
The last letter of 'sugar' is 'r'.
'latte'+'r'='LATTER'
'is' acts as a link.
(Other definitions for latter that I've seen before include "That follows" , "Rattle (anag.)" , "The one just mentioned" , "Last-mentioned" , "Second-mentioned of two" .)