The primary alien is alive and, worryingly, can defy gravity (8)
I believe the answer is:
levitate
'worryingly can defy gravity' is the definition.
I can't judge whether this defines the answer.
'the primary alien is alive' is the wordplay.
I cannot quite see how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found in the answer.
an anagram of 'alive' is 'levia' which is located in the remaining letters.
The remaining letters 'te' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
'and' acts as a link.
Can you help me to learn more?
(Other definitions for levitate that I've seen before include "Rise in the air, unsupported" , "Cause to rise and hover" , "Lift" , "Float magically in air" , "Rise and float in defiance of gravity" .)