Requests worker to be well-mannered (8)
I believe the answer is:
pleasant
'be well-mannered' is the definition.
(thesaurus)
'requests worker' is the wordplay.
'requests' becomes 'pleas' (plea is a kind of request).
'worker' becomes 'ant' (worker is a type of ant).
'pleas'+'ant'='PLEASANT'
'to' is the link.
(Other definitions for pleasant that I've seen before include "A greeable, affable" , "sweet?" , "Nice, satisfying" , "Refreshing" , "Attractive" .)