Imagine another time when ruined terrace’s laid over earth (8)
I believe the answer is:
recreate
'imagine another time' is the definition.
(as in recreating an earlier time or event)
'ruined terrace's laid over earth' is the wordplay.
'ruined' is an anagram indicator.
'laid over' means one lot of letters go next to another (in a down clue, some letters go above others).
'earth' becomes 'e'.
'terrace' with letters rearranged gives 'recreat'.
'recreat'+'e'='RECREATE'
'when' acts as a link.
(Other definitions for recreate that I've seen before include "Bring back" , "design again" , "Produce again" .)