Dog muck outside of church (5)
I believe the answer is:
pooch
'dog' is the definition.
(pooch is a kind of dog)
'muck outside of church' is the wordplay.
'muck' becomes 'poo' (informal term for excrement).
'outside of' says to hollow out the word (remove centre letters).
'church' with its middle removed is 'ch'.
'poo'+'ch'='POOCH'
(Other definitions for pooch that I've seen before include "one of our best friends" , "Doggy" , "Dog (colloq.)" .)