Parson always last on run (8)
I believe the answer is:
reverend
'parson' is the definition.
(thesaurus)
'always last on run' is the wordplay.
'always' becomes 'ever' (synonyms).
'last' becomes 'end' (I've seen this in another clue).
'on' means one lot of letters go next to another.
'run' becomes 'r' (cricket abbreviation).
'ever'+'end'='everend'
'everend' after 'r' is 'REVEREND'.
(Other definitions for reverend that I've seen before include "Clergyman's title" , "(Form of address to) clergyman" , "like Father Brown" , "Mother may go after this" , "Cleric's title" .)