Dependant requiring a command to be in place (9)
I believe the answer is:
satellite
'dependant' is the definition.
(thesaurus)
'a command to be in place' is the wordplay.
'command' becomes 'tell' (tell or command someone to do something).
'to be in' indicates putting letters inside.
'place' becomes 'site' (site is a kind of place).
'a'+'tell'='atell'
'atell' inserted into 'site' is 'SATELLITE'.
'requiring' acts as a link.
(Other definitions for satellite that I've seen before include "Space traveller" , "space station, perhaps" , "Part of telecoms system" , "Any celestial body orbiting around a planet or star" , "Body in orbit around another" .)