Nice entreaties by social worker (8)
I believe the answer is:
pleasant
'nice' is the definition.
(similar in meaning)
'entreaties by social worker' is the wordplay.
'entreaties' becomes 'pleas' (plea is a kind of entreaty).
'by' means one lot of letters go next to another.
'social worker' becomes 'ant' (ants are social insects).
'pleas'+'ant'='PLEASANT'
(Other definitions for pleasant that I've seen before include "Delightful" , "Charming" , "Satisfying, likeable" , "Refreshing" , "Attractive" .)