Bishop managed to get some roughage (4)
I believe the answer is:
bran
'some roughage' is the definition.
(bran is a kind of roughage)
'bishop managed' is the wordplay.
'bishop' becomes 'B' (chess abbreviation).
'managed' becomes 'ran' (I've seen this before).
'b'+'ran'='BRAN'
'to get' acts as a link.
(Other definitions for bran that I've seen before include "Fibre cereal" , "Healthy breakfast" , "Husks of cereal seeds sifted from flour" , "Husks of corn" , "Outer covering of grain" .)