Masculine decoration catching zip has gotta hurt (9)
I believe the answer is:
moustache
'masculine decoration' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'catching zip has gotta hurt' is the wordplay.
'catching' means one lot of letters goes inside another.
'zip has' becomes 'o' (I can't justify this - if you can you should give a lot more credence to this answer).
'gotta' becomes 'must' (I've seen this in another clue).
'hurt' becomes 'ache' (synonyms).
'o' inserted into 'must' is 'moust'.
'moust'+'ache'='MOUSTACHE'
Can you help me to learn more?
(Other definitions for moustache that I've seen before include "Hair on upper lip" , "Facial adornment" , "Handlebar or walrus, for example" , "Food trap" , "Walrus, e.g." .)