Fix material next to display (6)
I believe the answer is:
repair
'fix' is the definition.
(to fix something is to repair it)
'material next to display' is the wordplay.
'material' becomes 'rep' (rep is a kind of material).
'next to' means one lot of letters go next to another.
'display' becomes 'air' (I've seen this in another clue).
'rep'+'air'='REPAIR'
(Other definitions for repair that I've seen before include "Restore after damage" , "Get back into good shape" , "Once, return" , "Travel or proceed toward some place" , "Restore; go" .)