It's obtained from Baker Street's west side with the cash we have (9)
I believe the answer is:
sourdough
'it's obtained from baker' is the definition.
(a baker might bake sourdough)
'street's west side with the cash we have' is the wordplay.
'west side' suggests taking the first letters (the letter on the west end of the word).
'with' says to put letters next to each other.
'the cash we have' becomes 'ourdough' (dough can mean money).
The first letter of 'streets' is 's'.
's'+'ourdough'='SOURDOUGH'
(Other definitions for sourdough that I've seen before include "Leaven for making bread" , "Fermenting bread mixture - odour hugs (anag)" , "Type of bread" .)