Wind — trees lay broken (8)
I believe the answer is:
easterly
'wind' is the definition.
(I know that easterly is a type of wind)
'trees lay broken' is the wordplay.
'broken' indicates an anagram.
'trees'+'lay'='treeslay'
'treeslay' anagrammed gives 'EASTERLY'.
(Other definitions for easterly that I've seen before include "Of wind, blowing from direction of rising sun" , "Year's let (anag) - direction of 15" , "Wind coming from Britain, say" , "bitter blow for the UK" , "Wind to westward" .)