Casual feature of grain for malting (8)
I believe the answer is:
informal
'casual' is the definition.
(similar in meaning)
'feature of grain for malting' is the wordplay.
'feature of' says the answer is hidden in the clue.
'INFORMAL' is hidden within 'grain for malting'.
(Other definitions for informal that I've seen before include "Casual, not official" , "Casual and unceremonious" , "Unofficial, relaxed" , "Casual or unofficial" , "Casual, free and easy" .)