Obsession can be about right for an airman (5)
I believe the answer is:
'obsession' is the definition.
(I've seen this before)
'about right for an airman' is the wordplay.
I cannot really see how this works, but
'about' could be 'a' (abbreviation in Chambers) and 'a' is found in the answer.
'an' could be 'i' (Roman numeral for one) and 'i' is found in the answer.
The remaining letters 'mna' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'can be' is the link.
Can you help me to learn more?
(Other definitions for mania that I've seen before include "Aberration" , "Excessive enthusiasm" , "wildness" , "Passion -- mood disorder" , "Violent madness or extreme enthusiasm" .)