Own a section of Fifth Avenue (4)
I believe the answer is:
have
'own' is the definition.
(synonyms)
'a section of fifth avenue' is the wordplay.
'a section of' indicates the answer is hidden within the clue.
'HAVE' can be found hidden inside 'fifth avenue'.
(Other definitions for have that I've seen before include "Possess" , "Take" , "Enjoy yourself!" .)