The most common and most likely answer to this crossword clue is the 7 plus 8 letter word LIBERAL DEMOCRAT
I've seen this crossword clue in The Times
L
I
B
E
R
A
L
D
E
M
O
C
R
A
T
More clues leading to the result LIBERAL DEMOCRAT
- MP free before trial? Case not closed
- Crime lord able to corrupt visiting politician
- Wildly belt more radical party member
- Someone in the party’s ribald dancing with latecomer
- Party member’s unsparing protest about traitor
- Cable, say, displaced or trim lead with cable?
- MP, possibly a Brit, called more corrupt …
- Politician making electoral bid, arm having been twisted
- Drug in scales turning me cold; inform party person
- Politician, unusually calm deliberator
Buddy explains!
The straight part
We know that "party member" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case party member = liberal democrat.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.