Surrey town in memo spelt the wrong way (5)
I believe the answer is:
epsom
'surrey town' is the definition.
(I've seen this before)
'in memo spelt the wrong way' is the wordplay.
'in' indicates a hidden word.
'the wrong way' shows that the letters should be reversed in order.
'mospe' is hidden within 'memo spelt'.
'mospe' written backwards gives 'EPSOM'.
(Other definitions for epsom that I've seen before include "Mopes around English Derby venue" , "Derby and Oaks racecourse" , "Town with racecourse" , "Home to the Derby and the Oaks" , "English racecourse" .)