Holy messenger curing a gerbil (7)
I believe the answer is:
gabriel
'holy messenger' is the definition.
(I've seen this in another clue)
'curing a gerbil' is the wordplay.
'curing' indicates anagramming the letters.
'a'+'gerbil'='agerbil'
'agerbil' anagrammed gives 'GABRIEL'.
(Other definitions for gabriel that I've seen before include "Chief guard of Paradise" , "Archangel and messenger of God" , "Man'" , "Trumpet-playing archangel who heralded good news" , "The angel with a trumpet" .)