Stick poster in this place (6)
I believe the answer is:
adhere
'stick' is the definition.
(to adhere to something is to stick to it)
'poster in this place' is the wordplay.
'poster' becomes 'ad' (short for advert).
'in this place' becomes 'here' (synonyms).
'ad'+'here'='ADHERE'
(Other definitions for adhere that I've seen before include "Stick or cleave to" , "Stick to, remain loyal" , "Stick L" , "Stick to or remain faithful" , "paste" .)