Dull clergyman touring Dordogne on vacation (6)
I believe the answer is:
deaden
'dull' is the definition.
(I've seen this in another clue)
'clergyman touring dordogne on vacation' is the wordplay.
'clergyman' becomes 'dean' (dean is a kind of clergyman).
'touring' indicates putting letters inside (touring can mean going round).
'on vacation' suggests removing the centre (after the inside letters have vacated the word).
'dordogne' with its middle taken out is 'de'.
'dean' enclosing 'de' is 'DEADEN'.
(Other definitions for deaden that I've seen before include "Dampen" , "Make insensitive" , "Muffle impact" , "Muffle (sound)" , "Make weaker or quieter" .)