Memento queen left in ice for restoring (5)
I believe the answer is:
relic
'memento' is the definition.
(a relic is an antique or memento)
'queen left in ice for restoring' is the wordplay.
'queen' becomes 'r' (abbreviation for regina, e.g. in ER ).
'left' becomes 'L' (common abbreviation).
'in' means one lot of letters goes inside another.
'for restoring' indicates an anagram.
'ice' anagrammed gives 'eic'.
'l' placed within 'eic' is 'elic'.
'r'+'elic'='RELIC'
(Other definitions for relic that I've seen before include "Holy remnant" , "Revered religious remnant" , "Abandoned item" , "Paper craft" , "Saint's body part?" .)