Assistant forgoing record tax (4)
I believe the answer is:
duty
'tax' is the definition.
(duty can mean a tax or toll)
'assistant forgoing record' is the wordplay.
'assistant' becomes 'deputy' (both can mean a second-in-command).
'forgoing' is a deletion indicator.
'record' becomes 'EP' (abbreviation for extended play record).
'deputy' with 'ep' taken away is 'DUTY'.
(Other definitions for duty that I've seen before include "Cancel (a law)" , "Government tax" , "Moral or legal obligation" , "Tax on goods" , "Financial or work obligation" .)