Rook destroyed tree at sanctuary (7)
I believe the answer is:
retreat
'sanctuary' is the definition.
(retreat can mean a sanctuary or hideout)
'rook destroyed tree at' is the wordplay.
'rook' becomes 'r' (chess abbreviation).
'destroyed' is an anagram indicator.
'tree'+'at'='treeat'
'treeat' is an anagram of 'etreat'.
'r'+'etreat'='RETREAT'
(Other definitions for retreat that I've seen before include "Withdraw from battle" , "hermitage, perhaps" , "Go back" , "Climb down" , "Take flight" .)