Axe the liar, needing change — cheer up, bigly (10)
I believe the answer is:
exhilarate
'cheer up bigly' is the definition.
I can't judge whether this defines the answer.
'axe the liar needing change' is the wordplay.
'needing change' indicates an anagram (I've seen 'needs changing' mean this (I've seen this in other clues)).
'axe'+'the'+'liar'='axetheliar'
'axetheliar' is an anagram of 'EXHILARATE'.
Can you help me to learn more?
(Other definitions for exhilarate that I've seen before include "Enliven" , "Make very happy or very animated" , "Thrill" , "Cheer" .)