Bishop once said to be struggling (8)
I believe the answer is:
diocesan
'bishop' is the definition.
(diocesan is a kind of bishop)
'once said to be struggling' is the wordplay.
'to be struggling' indicates an anagram.
'once'+'said'='oncesaid'
'oncesaid' with letters rearranged gives 'DIOCESAN'.
(Other definitions for diocesan that I've seen before include "Relating to a bishop's area" , "See description" , "Bishop; is deacon (anag.)" , "Relating to a bishop's district" , "Looking to see" .)