A way to start a timber store (5)
I believe the answer is:
stash
'store' is the definition.
(I know that stash is a type of store)
'a way to start a timber' is the wordplay.
'a way' becomes 'st' (short for street).
'to start' is a charade indicator (letters next to each other).
'a timber' becomes 'ash' (I've seen this before).
'st'+'ash'='STASH'
(Other definitions for stash that I've seen before include "Stow; secret store" , "Hide (something) away" , "Squirrel away" , "drug store" , "Cache" .)