Whitechapel killer in empty factory finding trifles (8)
I believe the answer is:
frippery
'trifles' is the definition.
(I've seen this before)
'whitechapel killer in empty factory' is the wordplay.
'whitechapel killer' becomes 'ripper' (serial killer Jack the Ripper).
'in' is an insertion indicator.
'empty' says to hollow out the word (remove centre letters).
'factory' with its centre taken out is 'fy'.
'ripper' inserted into 'fy' is 'FRIPPERY'.
'finding' acts as a link.
(Other definitions for frippery that I've seen before include "Showy ornament" , "Unnecessary ornamentation" , "Trifles" , "Unnecessary ornament" , "Tawdry finery" .)