One might help you get off a party island (5)
I believe the answer is:
alibi
'one might help you get' is the definition.
I can't tell whether this definition defines the answer.
'a party island' is the wordplay.
'party' becomes 'lib' (abbreviation for Liberal, uk political party).
'island' becomes 'i' (geographical abbreviation).
'a'+'lib'+'i'='ALIBI'
'off' is the link.
Can you help me to learn more?
(Other definitions for alibi that I've seen before include "Justification" , "excuse given" , "Evidence one was not at crime scene" , "Legal defence, plea" , "Defence against accusation - was seen elsewhere at the time" .)