Spacecraft for leaderless tribe on the move (7)
I believe the answer is:
orbiter
'spacecraft' is the definition.
(I know that spacecraft can be written as orbiter)
'for leaderless tribe on the move' is the wordplay.
'leaderless' means to remove the first letter.
'on the move' is an anagram indicator.
'for' with its first letter taken away is 'or'.
'tribe' anagrammed gives 'biter'.
'or'+'biter'='ORBITER'
(Other definitions for orbiter that I've seen before include "Circling spacecraft" , "Satellite perhaps" , "Space vehicle" , "Non-landing spacecraft" , "Craft going round planet" .)