One drunken smoker irritating (7)
I believe the answer is:
irksome
'irritating' is the definition.
(I've seen this before)
'one drunken smoker' is the wordplay.
'one' becomes 'i' (Roman numeral).
'drunken' indicates anagramming the letters.
'smoker' anagrammed gives 'rksome'.
'i'+'rksome'='IRKSOME'
(Other definitions for irksome that I've seen before include "Tediously annoying" , "Bothersome, annoying" , "Smoker I find annoying" , "bugging" , "'Tedious, tiresome (7)'" .)