Narrow lane, maybe (4)
I believe the answer is:
lean
'narrow' is the definition.
(thesaurus)
'lane maybe' is the wordplay.
'maybe' is an anagram indicator.
'lane' is an anagram of 'LEAN'.
(Other definitions for lean that I've seen before include "Incline; without fat" , "Thin; heel" , "director in past" , "Thin; rest (against)" , "Slope; thin" .)