The first person I answer, after computer nut (9)
I believe the answer is:
macadamia
'nut' is the definition.
(type of nut)
'the first person i answer after computer' is the wordplay.
'the first person' becomes 'adam' (biblical first person created).
'answer' becomes 'a' (abbreviation eg in Q and A).
'after' says to put letters next to each other.
'computer' becomes 'Mac' (Apple Mac computer).
'adam'+'i'+'a'='adamia'
'adamia' put after 'mac' is 'MACADAMIA'.
(Other definitions for macadamia that I've seen before include "Edible nut" , "Queensland nut" , "(Of drug) causing dependency" , "Nut-bearing tree" , "nut-tree" .)