Loan shark employer admits game being up (6)
I believe the answer is:
usurer
'loan shark' is the definition.
('usurer' can be a synonym of 'loan shark')
'employer admits game being up' is the wordplay.
'employer' becomes 'user' (I've seen this before).
'admits' indicates putting letters inside.
'game' becomes 'ru' (rugby union).
'being up' shows that the letters should be reversed in order (in down clue: letters go upwards).
'ru' in reverse letter order is 'ur'.
'user' enclosing 'ur' is 'USURER'.
(Other definitions for usurer that I've seen before include "Person taking a lot of interest" , "Shylock's profession" , "One lending money at unreasonable rates" , "Unscrupulous moneylender" , "One who exacts much interest on loans." .)