Head east, the wrong way, to reach city on the Ruhr (5)
I believe the answer is:
essen
'city on the ruhr' is the definition.
(German city on the Ruhr river)
'head east the wrong way' is the wordplay.
'head' becomes 'ness' (ness is a headland).
'east' becomes 'e' (synonyms).
'the wrong way' shows that the letters should be reversed in order.
'ness'+'e'='nesse'
'nesse' reversed gives 'ESSEN'.
'to reach' acts as a link.
(Other definitions for essen that I've seen before include "German industrial centre" , "European city" , "city in the Ruhr valley" , "German industrial city on the Ruhr" , "Industrial centre of the Ruhr" .)