Whispering wino needs to articulate 'I must go' (5,4)
I believe the answer is:
sotto voce
'whispering' is the definition.
(sotto voce is speaking quietly or whispering)
'wino needs to articulate i must go' is the wordplay.
'wino needs' becomes 'sot' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'articulate' becomes 'voice' (to voice is to articulate or express).
'must go' indicates named letters should be taken away.
'voice' with 'i' removed is 'voce'.
'sot'+'to'+'voce'='SOTTO VOCE'
(Other definitions for sotto voce that I've seen before include "In an undertone from Italy" , "Spoken quietly" , "Speaking quietly" , "on the quiet" , "In an undertone, from Italian" .)