Social worker entering factory with a Spanish scarf (8)
I believe the answer is:
'spanish scarf' is the definition.
(I've seen this in another clue)
'social worker entering factory with a' is the wordplay.
'social worker' becomes 'ant' (ants are social insects).
'entering' indicates putting letters inside.
'factory' becomes 'mill' (mill is a type of factory).
'with' means one lot of letters go next to another.
'ant' inserted into 'mill' is 'mantill'.
(Other definitions for mantilla that I've seen before include "head cover" , "Scarf held up by ornamental comb" , "covering for the head" , "Lace veil worn on head by Spanish women" , "sort of scarf" .)