Source of timber for building forts out East (6)
I believe the answer is:
forest
'source of timber' is the definition.
'forest' can be an answer for 'timber' (synonyms). I am not certain of the 'source of' bit.
'building forts out east' is the wordplay.
'building' is an anagram indicator.
'out' is an insertion indicator.
'east' becomes 'e' (abbreviation).
'forts' is an anagram of 'forst'.
'forst' enclosing 'e' is 'FOREST'.
'for' acts as a link.
Can you help me to learn more?
(Other definitions for forest that I've seen before include "Dense woodland" , "Thick growth of trees" , "Area thick with trees" , "Land covered with trees" , "Large wood" .)