Going too far, I had to retreat? You can say that again (5)
I believe the answer is:
ditto
'you can say that again' is the definition.
(I've seen this in another clue)
'going too far i had to retreat?' is the wordplay.
'going too far' becomes 'OTT' (short for over the top).
'i had' becomes 'i'd' (contraction).
'to retreat?' says the letters should be written backwards (I've seen 'retreating' mean this).
'ott'+'id'='ottid'
'ottid' written backwards gives 'DITTO'.
(Other definitions for ditto that I've seen before include "Same again, indicated by two dots" , "Mark used to indicate the word above it should be repeated" , "Duplicate" , "Two small marks indicating the same again" , "As given above" .)