Measure for an egg drink with alcoholic spirit (6)
I believe the answer is:
noggin
'measure' is the definition.
(I have seen 'Small measure' mean 'noggin' so perhaps 'measure' could also mean 'noggin')
'an egg drink with alcoholic spirit' is the wordplay.
'an egg drink' becomes 'nog' (I've seen this in another clue).
'with' says to put letters next to each other.
'alcoholic spirit' becomes 'gin' (I've seen this before).
'nog'+'gin'='NOGGIN'
'for' is the link.
(Other definitions for noggin that I've seen before include "Small measure of spirits or mug" , "Small mug - wooden cup" , "Head - tot" , "Small measure of alcohol, about 1/4 pint" , "Small measure of spirits or slangy head" .)