Private near front in theory (6)
I believe the answer is:
closet
'private' is the definition.
(similar in meaning)
'near front in theory' is the wordplay.
'near' becomes 'close' (synonyms).
'front in' suggests taking the first letters (I've seen 'fronts in' mean this (the letters are the front)).
The initial letter of 'theory' is 't'.
'close'+'t'='CLOSET'
(Other definitions for closet that I've seen before include "Study" , "Confine" , "Compartment for clothing in the US" , "Small room or wardrobe" , "A small room - best to come out of it" .)