Processed mincemeat I had originally: that takes us back! (4,7)
I believe the answer is:
time machine
'that takes us back' is the definition.
'processed mincemeat i had originally' is the wordplay.
'processed' indicates anagramming the letters.
'originally' suggests taking the first letters.
The initial letter of 'had' is 'h'.
'mincemeat'+'i'+'h'='mincemeatih'
'mincemeatih' is an anagram of 'TIME MACHINE'.
(Other definitions for time machine that I've seen before include "Might this take you back?" , "Eg, Doctor Who's Tardis" .)