Concerned with voguish frame of reference (2,2)
I believe the answer is:
in re
'concerned with' is the definition.
(I've seen this in another clue)
'voguish frame of reference' is the wordplay.
'voguish' becomes 'in'.
'frame of' says to hollow out the word (remove centre letters) (use the outside letters which frame the word).
'reference' becomes 'rule' (rule is a kind of reference).
'rule' with its centre removed is 're'.
'in'+'re'='IN RE'
(Other definitions for in re that I've seen before include "With regard to" , "In the matter of (Lat.)" , "Concerning (L)" .)