Ref rants about substitution (8)
I believe the answer is:
transfer
'substitution' is the definition.
(transferring something else)
'ref rants about' is the wordplay.
'about' indicates an anagram.
'ref'+'rants'='refrants'
'refrants' is an anagram of 'TRANSFER'.
(Other definitions for transfer that I've seen before include "Make over (property to another)" , "Removal" , "Exchange" , "Change to another group or surface" , "Footballer maybe" .)