Secretly being very drunk (5,3,5)
I believe the answer is:
under the table
I believe this is a double definition.
'secretly' is the first definition.
(I've seen this before)
'very drunk' is the second definition.
'being' is the link.
(Other definitions for under the table that I've seen before include "Hopelessly drunk" , "footsie may be played here" , "secretly" , "Transacted in secret - sozzled" , "Not above board" .)