Dog collar's hem old parson turned up? (5)
I believe the answer is:
rover
'dog' is the definition.
(I've seen this before)
'collar's hem old parson turned up?' is the wordplay.
'hem' says to take the final letters (hem can mean an edge of something).
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'parson' becomes 'rev' (I've seen this in other clues).
'turned up?' is a reversal indicator.
The final letter of 'collar' is 'r'.
'rev' backwards is 'ver'.
'r'+'o'+'ver'='ROVER'
(Other definitions for rover that I've seen before include "Nomad" , "gypsy" , "Car - dog" , "Wanderer, rolling stone" , "Vehicle driven remotely over extraterrestrial terrain" .)