Pushy people conceal promotion (4)
I believe the answer is:
hype
'promotion' is the definition.
(I know that hype is a type of promotion)
'pushy people conceal' is the wordplay.
'conceal' indicates the answer is hidden within the clue.
'HYPE' is hidden in the letters of 'pushy people'.
(Other definitions for hype that I've seen before include "A promoter" , "Excess publicity" , "Doer of dirty work" , "Overblown publicity" , "Shrewd publicity" .)