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' says the letters should be written in reverse.
'to'+'l'='tol'
'tol' in reverse letter order is '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" .)