Preferred not to have a soft referee, but was wrong (5)
I believe the answer is:
erred
'was wrong' is the definition.
(I've seen this before)
'preferred not to have' is the wordplay.
'to have' indicates the answer is hidden within the clue.
'ERRED' is hidden within 'preferred not'.
'a soft referee but' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for erred that I've seen before include "slipped up" , "Gone astray!" , "Strayed from the straight and narrow" , "Committed a sin" , "Went astray" .)