Getting drunk during New Year is a fact of life (7)
I believe the answer is:
reality
'fact of life' is the definition.
'reality' can be an answer for 'fact' (I've seen this before). I'm not certain of the 'of life' bit.
'getting drunk during new year' is the wordplay.
'getting drunk' becomes 'lit' (I can't explain this - if you can you should give a lot more credence to this answer).
'during' indicates putting letters inside.
'new' indicates an anagram.
'year' is an anagram of 'reay'.
'lit' put inside 'reay' is 'REALITY'.
'is a' is the link.
Can you help me to learn more?
(Other definitions for reality that I've seen before include "as some TV programmes purport to show" , "Actual existence" , "All that is actual and not imaginary" , "Fact" , "Type of television" .)