One making barrels of cash primarily loves a ... (6)
I believe the answer is:
cooper
'one making barrels' is the definition.
(a cooper is a barrel maker)
'cash primarily loves a' is the wordplay.
'primarily' indicates taking the first letters.
'loves' becomes 'oo' (love means 0 in tennis).
'a' becomes 'per' (eg 'one a day' means 'one per day').
The first letter of 'cash' is 'c'.
'c'+'oo'+'per'='COOPER'
'of' is the link.
(Other definitions for cooper that I've seen before include "Cask/barrel maker" , "Porter with stout" , "Cask and barrel maker" , "Cask-maker" , "Craftsman" .)