Consequently European umpire gets involved in other foul (9)
I believe the answer is:
therefore
'consequently' is the definition.
(I know that consequently can be written as therefore)
'european umpire gets involved in other foul' is the wordplay.
'european' becomes 'E' (abbreviation e.g. EU).
'umpire' becomes 'ref' (short for referee).
'gets involved in' means one lot of letters goes inside another.
'foul' indicates anagramming the letters.
'e'+'ref'='eref'
'other' is an anagram of 'thore'.
'eref' inserted into 'thore' is 'THEREFORE'.
(Other definitions for therefore that I've seen before include "Thus" , "It follows" , "Consequently - for that reason" , "In consequence" , "Ergo" .)