Wingtip-to-wingtip measure
I believe the answer is:
span
'wingtip-to-wingtip measure' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for span that I've seen before include "Bridge or range" , "Measurement between tips of thumb, little finger" , "Stretch < fresh" , "Ox team; bridge" , "Pair of horses" .)