“Moose-ling” could be a recent addition to dictionary (9)
I believe the answer is:
neologism
'a recent addition to dictionary' is the definition.
I can't tell whether this defines the answer.
'moose-ling could be' is the wordplay.
'could be' is an anagram indicator.
'moose'+'ling'='mooseling'
'mooseling' is an anagram of 'NEOLOGISM'.
Can you help me to learn more?
(Other definitions for neologism that I've seen before include "Newly coined word" , "New word or phrase" , "coinage" , "Brexit maybe" , "new term" .)