A vicar agog to recollect old master (10)
I believe the answer is:
'old master' is the definition.
(I know that Caravaggio is an old master)
'a vicar agog to recollect' is the wordplay.
'to recollect' indicates anagramming the letters.
'avicaragog' is an anagram of 'CARAVAGGIO'.
(Other definitions for caravaggio that I've seen before include "Italian painter known for contrasts of light/shade" , "Italian painter, d. 1610" , "Supper at Emmaus painter" , "Italian Baroque painter (d.1610)" , "Artist" .)