Chief method of movement? (7)
I believe the answer is:
headway
'movement?' is the definition.
(I know that headway is a type of change of location)
'chief method' is the wordplay.
'chief' becomes 'head' (synonyms).
'method' becomes 'way' (way of doing something).
'head'+'way'='HEADWAY'
'of' is the link.
(Other definitions for headway that I've seen before include "Progress or forward motion" , "Progress or success in work" , "Ground" , "Advance" , "Progress, forward movement" .)