Level crossing the writer will support (6)
I believe the answer is:
pillar
'support' is the definition.
(pillar is a kind of support)
'level crossing the writer will' is the wordplay.
'level' becomes 'par' (I have seen 'Accepted level ' mean 'par' so perhaps 'level' could also mean 'par').
'crossing' indicates putting letters inside.
'the writer will' becomes 'ill' (I'll, i.e. 'the person writing the crossword will').
'par' placed around 'ill' is 'PILLAR'.
(Other definitions for pillar that I've seen before include "Vertical cylindrical structure" , "Column; admired member (of community)" , "Stylite would live on it" , "Architectural support" , "Tall support" .)