Right in seeing that sci-fi classic (6)
I believe the answer is:
aliens
'sci-fi classic' is the definition.
Although both the answer and 'classic' are nouns, they are not in the same form of the noun.
'right in seeing that' is the wordplay.
'right' becomes 'lien' (legal right).
'in' means one lot of letters goes inside another.
'seeing that' becomes 'as' (I've seen this in other clues).
'lien' inserted within 'as' is 'ALIENS'.
Can you help me to learn more?
(Other definitions for aliens that I've seen before include "Outsiders" , "Forms of life assumed to exist outside Earth" , "Strangers, extraterrestrials" , "Life-forms assumed to exist beyond Earth" , "Strange forms of life" .)