Nasty, the German wind (7)
I believe the answer is:
meander
'wind' is the definition.
(to meander is to wind around)
'nasty the german' is the wordplay.
'nasty' becomes 'mean' (similar in meaning).
'the german' becomes 'der' ('the' in German).
'mean'+'der'='MEANDER'
(Other definitions for meander that I've seen before include "Ramble about aimlessly" , "Roam aimlessly around" , "Renamed (anag)" , "Aimless course" , "Wander aimless" .)