Clock put back by star (7)
I believe the answer is:
sundial
'clock' is the definition.
'put back by star' is the wordplay.
'put' becomes 'laid' (I've seen this before).
'back' shows that the letters should be reversed in order.
'by' says to put letters next to each other.
'star' becomes 'sun' (Sun is an example).
'laid' in reverse letter order is 'dial'.
'dial' after 'sun' is 'SUNDIAL'.
(Other definitions for sundial that I've seen before include "Light clock" , "Indicator of time" , "Outdoor timing device" , "Solar timepiece" , "Shadow clock" .)