Alternatively find one on stars (5)
I believe the answer is:
orion
'stars' is the definition.
(Orion is a constellation)
'alternatively find one on' is the wordplay.
'alternatively' becomes 'or'.
'find' means one lot of letters go next to another.
'one' becomes 'I' (Roman numeral).
'or'+'i'+'on'='ORION'
(Other definitions for orion that I've seen before include "Mythical great hunter" , "Hunter slain by Artemis" , "Group of stars" , "Heavenly figure" , "Constellation on the celestial equator -- giant hunter of Greek mythology" .)