Intend to accompany aliens arriving at Venus and Mars? (7)
I believe the answer is:
planets
'venus and mars?' is the definition.
(I've seen this in another clue)
'intend to accompany aliens' is the wordplay.
'intend' becomes 'plan' (planning is a kind of intending).
'to accompany' means one lot of letters go next to another.
'aliens' becomes 'ETs' (ET is short for extraterrestrial).
'plan'+'ets'='PLANETS'
'arriving at' is the link.
(Other definitions for planets that I've seen before include "Big bodies" , "Heavenly bodies" , "Celestial bodies" , "Ten laps (anag.)" .)