Get liberal in party a big majority (9)

I believe the answer is:

landslide

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'a big majority' is the definition.
(I've seen this before)

'get liberal in party' is the wordplay.
'get' becomes 'land' (landing is a kind of getting).
'liberal in party' becomes 'slide' (I am not sure about this - if you are sure you should believe this answer much more).
'land'+'slide'='LANDSLIDE'

Can you help me to learn more?

(Other definitions for landslide that I've seen before include "Major earth movement" , "Overwhelming victory in election, or a natural disaster" , "convincing victory" , "Overwhelming election majority" , "easy victory" .)

I've seen this clue in The Telegraph.

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