Main part of the rugby team has moved on (5,5)
I believe the answer is:
lions share
'main part' is the definition.
(I've seen this before)
'the rugby team has moved on' is the wordplay.
'the rugby team' becomes 'lions' (British and Irish Lions).
'moved' is an anagram indicator.
'on' becomes 're' ('on' can be mean 'with reference to'**).
'has' anagrammed gives 'sha'.
'lions'+'sha'+'re'='LIONS SHARE'
'of' acts as a link.
(Other definitions for lions share that I've seen before include "Largest part" , "Principal part" , "For the greater part" , "Largest portion" , "Main part" .)