Beginning to make old equipment trendy (6)
I believe the answer is:
origin
'beginning' is the definition.
(I know that beginning can be written as origin)
'old equipment trendy' is the wordplay.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'equipment' becomes 'rig' (rig is a kind of equipment).
'trendy' becomes 'in' ('in' can mean fashionable).
'o'+'rig'+'in'='ORIGIN'
'to make' is the link.
(Other definitions for origin that I've seen before include "spring" , "Source, beginning point" , "Source - provenance" , "Square one" , "Where X meets Y" .)