One providing simple treatment as dog run over in robbery (9)
I believe the answer is:
herbalist
'one providing simple treatment' is the definition.
(someone providing herbal treatments)
'dog run over in robbery' is the wordplay.
'dog' becomes 'lab' (short for labrador).
'run' becomes 'r' (cricket abbreviation).
'over' shows that the letters should be reversed in order.
'in' indicates putting letters inside.
'robbery' becomes 'heist' (heist is a kind of robbery).
'lab'+'r'='labr'
'labr' written backwards gives 'rbal'.
'rbal' inserted into 'heist' is 'HERBALIST'.
'as' acts as a link.
(Other definitions for herbalist that I've seen before include "simple job" , "He dispenses simple cures" , "Early botanical writer" .)