Obsequious in writing about host (6)
I believe the answer is:
smarmy
'obsequious' is the definition.
(I've seen this before)
'writing about host' is the wordplay.
'writing' becomes 'ms' (abbreviation for manuscript).
'about' says the letters should be written in reverse.
'host' becomes 'army' (I've seen this before).
'ms' in reverse letter order is 'sm'.
'sm'+'army'='SMARMY'
'in' is the link.
(Other definitions for smarmy that I've seen before include "Fawning" , "Bootlicking" , "Obsequious" , "Excessively ingratiating" , "Excessively flattering (R, not L)" .)