Measure of spirits and half of bitter — walk unsteadily? (6)
I believe the answer is:
totter
'walk unsteadily?' is the definition.
(I've seen this before)
'measure of spirits and half of bitter' is the wordplay.
'measure of spirits' becomes 'tot' (I've seen this before).
'and' is a charade indicator (letters next to each other).
'half of' means to take half the letters.
'bitter' with half the letters taken is 'ter'.
'tot'+'ter'='TOTTER'
(Other definitions for totter that I've seen before include "Be unsteady on one's feet" , "Stagger, reel" , "Maybe a mathematician" , "Walk shakily as if about to fall" , "Wobble - rag-and-bone man" .)