Walrus, perhaps has to hurt crossing over (9)
I believe the answer is:
moustache
'walrus perhaps' is the definition.
(walrus is a type of moustache)
'has to hurt crossing over' is the wordplay.
'has to' becomes 'must' (I've seen this before).
'hurt' becomes 'ache' ('ache' can be a synonym of 'hurt').
'crossing' is an insertion indicator.
'over' becomes 'o' (cricket abbreviation).
'must'+'ache'='mustache'
'mustache' placed around 'o' is 'MOUSTACHE'.
(Other definitions for moustache that I've seen before include "Facial feature" , "legacy of Zapata?" , "Facial hair growth" , "whiskers" , "See 1" .)