Wing and tail feathers missing one month (8)
I believe the answer is:
transept
'wing' is the definition.
(I've seen this before)
'one month' is the wordplay.
'one' becomes 'tran' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'month' becomes 'Sept' (Sept is an example).
'tran'+'sept'='TRANSEPT'
'and tail feathers missing' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for transept that I've seen before include "Arm of church body" , "Part of a church at right angles to the nave" , "Patterns in part of church at right angle to nave" , "always running north to south" , "Part of church off aisle" .)