Wander beyond end of forest to find treasure (5)
I believe the answer is:
trove
'treasure' is the definition.
(trove is a kind of treasure)
'wander beyond end of forest' is the wordplay.
'wander' becomes 'rove' ('rove' can be a synonym of 'wander').
'beyond' means one lot of letters go next to another.
'end of' says to take the final letters.
The last letter of 'forest' is 't'.
'rove' put after 't' is 'TROVE'.
'to find' is the link.
(Other definitions for trove that I've seen before include "Hoard" , "hidden valuables" , "Pirates' treasure?" , "Treasure of unknown ownership" , "Finds" .)