Temporary worker at home perhaps resentful about curtailed opening (4-6)

'temporary worker at home perhaps' is the definition.
(person who works in one's home temporarily)

'resentful about curtailed opening' is the wordplay.
'resentful' becomes 'bitter' (synonyms).
'about' is an insertion indicator.
'curtailed' means to remove the last letter.
'opening' becomes 'abyss' (term for a void or gap).
'abyss' with its last letter taken off is 'abys'.
'bitter' going around 'abys' is 'BABY-SITTER'.