Stuff concerning father (5)
I believe the answer is:
padre
'father' is the definition.
(I know that father can be written as Padre)
'stuff concerning' is the wordplay.
'stuff' becomes 'pad' (padding is a kind of stuffing).
'concerning' becomes 're' (both can mean on a particular topic).
'pad'+'re'='PADRE'
(Other definitions for padre that I've seen before include "Man of god - drape (anag)" , "Father" , "Army chaplain" , "clerical worker" , "Priest, chaplain" .)