About poem being in secret language (4)
I believe the answer is:
code
'secret language' is the definition.
(I've seen this in another clue)
'about poem' is the wordplay.
'about' becomes 'c' (abbreviation for 'circa').
'poem' becomes 'ode' (ode is a kind of poem).
'c'+'ode'='CODE'
'being in' is the link.
This may not be right. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for code that I've seen before include "Secret system of letters. words etc" , "Ethical standards" , "regulations" , "System of ethics - cipher" , "System used to disguise or represent words, like Morse" .)