Monk (5)
(Other definitions for abbot that I've seen before include "friar" , "Father" , "Head of abbey" , "Head of monastery" , "Head monk" .)
'monk' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for friar that I've seen before include "Mendicant priest" , "Man connected with order" , "Monk perhaps" , "Mendicant preacher" , "Eg, a Franciscan" .)