Retreat from eager beaver's bossiness at first (3)
I believe the answer is:
ebb
'retreat' is the definition.
(I have seen 'Tidal retreat ' mean 'ebb' so perhaps 'retreat' could also mean 'ebb')
'eager beaver's bossiness at first' is the wordplay.
'at first' says to take the initial letters.
The initial letters of 'eager beavers bossiness' is 'EBB'.
'from' is the link.
(Other definitions for ebb that I've seen before include "Flow outwards" , "state of decline" , "recession" , "Not to wax" , "Type of tide" .)