Ruler from space periodically visited meteors (5)
I believe the answer is:
emeer
'ruler' is the definition.
('emeer' is a variant spelling of 'emir')
'space periodically visited meteors' is the wordplay.
'space' becomes 'em' (in typography, a space as wide as a letter 'm').
'periodically visited' means one should take alternating letters.
The alternate letters of 'meteors' are 'eer'.
'em'+'eer'='EMEER'
'from' is the link.
(Other definitions for emeer that I've seen before include "independent ruler" , "Islamic governor" , "Leader of Arabs" , "Islamic title" , "Meryl -, US actress" .)