Catwalk or airstrip (6)
I believe the answer is:
runway
This clue is a double definition.
'catwalk' is the first definition.
(thesaurus)
'airstrip' is the second definition.
(I've seen this before)
(Other definitions for runway that I've seen before include "Strip at the airport" , "Strip on which planes take off and land" , "Landing surface" , "Level stretch for aircraft" , "A plane takes off from it" .)