Unctuous and oddly lacking socially (4)
I believe the answer is:
oily
'unctuous' is the definition.
(I've seen this before)
'oddly lacking socially' is the wordplay.
'oddly lacking' indicates alternate letters.
The alternate letters of 'socially' are 'OILY'.
'and' acts as a link.
(Other definitions for oily that I've seen before include "Covered in lubricant" , "Like a lot of fish" , "Smoothly ingratiating" , "Smooth, ingratiating" , "Unpleasantly ingratiating" .)