Clergyman gets tongue back (7)
I believe the answer is:
reverse
'back' is the definition.
(back can mean to reverse)
'clergyman gets tongue' is the wordplay.
'clergyman' becomes 'rev' (I've seen this before).
'gets' says to put letters next to each other.
'tongue' becomes 'erse' (Erse is an example).
'rev'+'erse'='REVERSE'
(Other definitions for reverse that I've seen before include "Tails (of a coin)" , "Turn inside out or upside down" , "Transpose" , "Go in the opposite direction" , "contrary" .)