Informally against opening a gym in Norway (4)
I believe the answer is:
agin
'informally' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'against opening a gym in norway' is the wordplay.
'opening' suggests taking the first letters.
'a gym in norway' becomes 'gin' (this could be a standard abbreviation I've not previously seen).
The initial letter of 'against' is 'a'.
'a'+'gin'='AGIN'
Can you help me to learn more?
(Other definitions for agin that I've seen before include "Not in favour of" , "Hostile to" , "Dialect form of against" , "Not a fan of" , "Opposed to local" .)