Ingratiating — and regularly ignored socially (4)
I believe the answer is:
oily
'ingratiating' is the definition.
(I've seen this in another clue)
'regularly ignored socially' is the wordplay.
'regularly ignored' indicates alternate letters (letters removed at regular intervals).
The alternate letters of 'socially' are 'OILY'.
'and' acts as a link.
(Other definitions for oily that I've seen before include "Oleaginous" , "Covered in lubricant" , "Smooth; like lubricant" , "Unctuous" , "Greasy - obsequious" .)