American releases relatives (7)
I believe the answer is:
aunties
'relatives' is the definition.
(aunty is a kind of relative)
'american releases' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'releases' becomes 'unties' (releases someone tied up).
'a'+'unties'='AUNTIES'
(Other definitions for aunties that I've seen before include "Female relatives" , "Parent's sisters (informal)" , "Older female friends" , "older women" , "Female relations" .)