A wise guy was off road (5)
I believe the answer is:
swami
'a wise guy' is the definition.
(I've seen this in another clue)
'was off road' is the wordplay.
'off' indicates an anagram.
'road' becomes 'mi' (resembles M1 motorway).
'was' anagrammed gives 'swa'.
'swa'+'mi'='SWAMI'
(Other definitions for swami that I've seen before include "Religious master" , "How to address Hindu dignitary" , "Term of respect to a Hindu teacher" , "Hindu religious instructor" , "Hindu leader" .)