Part of hooter having indecisive sound after a month (6)
I believe the answer is:
septum
'part of hooter' is the definition.
'septum' can be an answer for 'part' (septum is a kind of part). I'm not certain of the 'of hooter' bit.
'indecisive sound after a month' is the wordplay.
'indecisive sound' becomes 'tum' (I can't explain this - if you can you should give a lot more credence to this answer).
'after' means one lot of letters go next to another.
'a month' becomes 'Sep' (abbreviation for September).
'tum' put after 'sep' is 'SEPTUM'.
'having' is the link.
Can you help me to learn more?
(Other definitions for septum that I've seen before include "Partition between two chambers" , "Division between nostrils" , "Dividing partition between the nostrils" , "Partition between two cavities of the nose" , "Partition in nose between nostrils" .)