Zero kit fashionable, for a start (6)
I believe the answer is:
origin
'for a start' is the definition.
(I've seen this in another clue)
'zero kit fashionable' is the wordplay.
'zero' becomes 'O' (O resembles 0).
'kit' becomes 'rig' (I've seen this before).
'fashionable' becomes 'in' (in can mean fashionable or trendy).
'o'+'rig'+'in'='ORIGIN'
(Other definitions for origin that I've seen before include "Crossing of axes" , "Source, beginning point" , "First thing" , "Place or point of beginning (6)" , "Beginning, starting point" .)