Emperor's naked signal for a drink (6)
I believe the answer is:
pernod
'for a drink' is the definition.
(Pernod is an example)
'emperor's naked signal' is the wordplay.
'naked' indicates the central letters (outside letters removed so centre is unclothed).
'signal' becomes 'nod' (I've seen this in another clue).
The middle letters of 'emperor' are 'per'.
'per'+'nod'='PERNOD'
(Other definitions for pernod that I've seen before include "Ponder on this liqueur" , "Ponder on anis drink" , "Aniseed-flavoured aperitif" , "Brand of pastis" , "French aperitif" .)