Berry pest affected elder (9)
I believe the answer is:
presbyter
'elder' is the definition.
(presbyter is a kind of elder)
'berry pest affected' is the wordplay.
'affected' indicates an anagram.
'berry'+'pest'='berrypest'
'berrypest' is an anagram of 'PRESBYTER'.
(Other definitions for presbyter that I've seen before include "Church elder" , "See member of church" , "Church minister" , "Kirk elder; Episcopalian minister ranking between bishop and deacon" .)