Wood in Chelmsford (3)
I believe the answer is:
elm
'wood' is the definition.
(elm is a kind of wood)
'in chelmsford' is the wordplay.
'in' indicates a hidden word.
'ELM' is hidden within 'chelmsford'.
(Other definitions for elm that I've seen before include "Tough timber" , "Stately tree" , "Forest tree" , "Tree for a Cockney tiller" , "Native British tree" .)