By getting round the referee, show favouritism! (6)
I believe the answer is:
prefer
'by getting round the referee show favouritism' is the definition.
I can't judge whether this defines the answer.
'by getting round the referee' is the wordplay.
'by' becomes 'per' (I've seen this in another clue).
'getting round' indicates putting letters inside.
'the referee' becomes 'ref' (synonyms).
'per' placed around 'ref' is 'PREFER'.
Can you help me to learn more?
(Other definitions for prefer that I've seen before include "Favour, like better" , "Choose over others" , "Promote; like better" , "Value more highly" , "as one may with charges" .)