Place of refreshment, old, unaltered (5)
I believe the answer is:
oasis
'place of refreshment' is the definition.
(I've seen this before)
'old unaltered' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'unaltered' becomes 'asis' (I've seen this in other clues).
'o'+'asis'='OASIS'
(Other definitions for oasis that I've seen before include "Desert refuge" , "Fertile tract in a desert" , "Florist's foam" , "Green area in desert" , "Fertile place like waterhole in desert" .)