Bachelors, I see, are fairly primitive (5)
I believe the answer is:
basic
'fairly primitive' is the definition.
'basic' can be an answer for 'primitive' (thesaurus). I'm not sure about the 'fairly' bit.
'bachelors i see' is the wordplay.
'bachelors' becomes 'bas' (I can't explain this - if you can you should believe this answer much more).
'see' becomes 'c' (the word for the letter, according to Chambers).
'bas'+'i'+'c'='BASIC'
'are' acts as a link.
Can you help me to learn more?
(Other definitions for basic that I've seen before include "vital" , "'Primary, fundamental (5)'" , "Straightforward" , "essential" , "Staple; ordinary" .)