She separates wheat from chaff so it's fresher in the East End (8)
I believe the answer is:
thresher
'she separates wheat from chaff' is the definition.
I can't tell whether this defines the answer.
'it's fresher in the east end' is the wordplay.
'it's' becomes 'th' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in the east end' means to remove the first letter (drop a letter, as a cockney might).
'fresher' with its initial letter taken off is 'resher'.
'th'+'resher'='THRESHER'
'so' acts as a link.
Can you help me to learn more?
(Other definitions for thresher that I've seen before include "Flail" , "Harvesting machine - type of shark" , "Machine used after harvesting" , "Machine separating grain from rest of plant" , "Grain separator; shark" .)