Anglo-Saxon writer in Colorado resort (5)
I believe the answer is:
aspen
'colorado resort' is the definition.
(Colorado ski resort)
'anglo-saxon writer' is the wordplay.
'anglo-saxon' becomes 'as' (abbreviation for Anglo-Saxon).
'writer' becomes 'pen' (I've seen this before).
'as'+'pen'='ASPEN'
'in' acts as a link.
(Other definitions for aspen that I've seen before include "Colorado ski resort - tree" , "Very timid" , "Tmorous" , "city in Colorado" , "A poplar with shivering leaves" .)