Material needed by worker and officer (8)
I believe the answer is:
sergeant
'officer' is the definition.
(I've seen this before)
'material needed by worker' is the wordplay.
'material' becomes 'serge' (serge is a kind of material).
'needed by' means one lot of letters go next to another.
'worker' becomes 'ant' (worker is a type of ant).
'serge'+'ant'='SERGEANT'
'and' acts as a link.
(Other definitions for sergeant that I've seen before include "Estrange (anag)" , "Pepper, say" , "Police rank" , "CARRY ON FILM" , "Troy" .)