Russell protects lines to one party in coalition (8)
I believe the answer is:
alliance
'coalition' is the definition.
('alliance' can be a synonym of 'coalition')
'russell protects lines to one party' is the wordplay.
I cannot quite understand how this works, but
'lines' could be 'll' (I've seen this in other clues) and 'll' is found within the answer.
'one' could be 'an' (I've seen this in other clues) and 'an' is present in the answer.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for alliance that I've seen before include "Combination by treaty" , "League - treaty" , "Group acting together for common cause" , "Kind of partnership with canaille" , "Bond" .)