Thoreau

3 clues
Author
Pond dweller
Friend of Emerson
Similar answers:
Abouthouse
Abouttheauthor
Acastofthousands
Accountholder
Actorthompson
Adoubtingthomas
Adulthood
Afterthought
Afterthoughts
Aheadwithoutit
Ahireauthority
Aljarreau
Allthoseagainst
Allthoseinfavor
Allthosemuscles
Altho
Althorn
Althorns
Although
Althoughtimeisa