One nerdy follower of Phi cracks themes on a regular basis (6)
I believe the answer is:
techie
'one nerdy follower' is the definition.
I don't know anything about this answer so I cannot tell whether it can be defined by this definition.
'phi cracks themes on a regular basis' is the wordplay.
'phi' becomes 'chi' (I can't explain this - if you can you should give a lot more credence to this answer).
'cracks' is an insertion indicator (inserted letters go into a gap or crack).
'on a regular basis' indicates alternate letters.
The alternating letters of 'themes' are 'tee'.
'chi' placed within 'tee' is 'TECHIE'.
'of' is the link.
Can you help me to learn more?
(Other definitions for techie that I've seen before include "Expert in some practical science" , "IT whizz" , "computer expert" , "PC expert" .)