Fairly drunk, tucking into beer - and nothing else? (5)
I believe the answer is:
alone
'and nothing else?' is the definition.
'fairly drunk tucking into beer' is the wordplay.
'fairly drunk' becomes 'on' (informal term meaning slightly drunk).
'tucking into' means one lot of letters goes inside another.
'beer' becomes 'ale' (I've seen this before).
'on' put within 'ale' is 'ALONE'.
(Other definitions for alone that I've seen before include "Single" , "Without others present" , "Without others being involved" , "without partner?" , "With no one to see" .)