In retro pub game, you once went amiss (7)
I believe the answer is:
strayed
'went amiss' is the definition.
'strayed' can be an answer for 'went' (straying is a kind of going). I am not certain of the 'amiss' bit.
'in retro pub game you' is the wordplay.
'in' is an insertion indicator.
'retro' shows that the letters should be reversed in order (retro is Latin for 'backwards').
'pub game' becomes 'darts' (I've seen this in another clue).
'you' becomes 'ye' (historical version of 'you').
'darts' in reverse letter order is 'strad'.
'strad' going around 'ye' is 'STRAYED'.
'once' acts as a link.
Can you help me to learn more?
(Other definitions for strayed that I've seen before include "Wandered; digressed" , "Went wrong" , "Went off violin" , "Went off the track" , "Wandered off course" .)