Much, to the Left, is retrograde (3)
I believe the answer is:
lot
'much' is the definition.
(I've seen this in other clues)
'to the left is retrograde' is the wordplay.
'the left' becomes 'l' (common abbreviation).
'is retrograde' is a reversal indicator.
'to'+'l'='tol'
'tol' written backwards gives 'LOT'.
(Other definitions for lot that I've seen before include "Portion in life" , "He left his wife without a backward glance" , "biblical refugee" , "Fate - plenty" , "Where filming may take place" .)