Instruments used in soap production? (6)
I believe the answer is:
pianos
'instruments' is the definition.
(piano is a kind of instrument)
'in soap production?' is the wordplay.
'production?' is an anagram indicator (I've seen 'production' mean this).
'in'+'soap'='insoap'
'insoap' is an anagram of 'PIANOS'.
'used' acts as a link.
(Other definitions for pianos that I've seen before include "Hammer and strings instruments" , "Chordophones with keys" , "strides?" , "Musical instruments like Steinways" , "Hammer-based instruments" .)