Short trousers? Soft soap (7)
I believe the answer is:
flannel
I believe this clue is a double definition.
'short trousers?' is the first definition.
(I've seen this before)
'soft soap' is the second definition.
(thesaurus)
(Other definitions for flannel that I've seen before include "hedge" , "Cloth for washing face, or just flattery" , "short trousers" , "Small piece of towelling for washing oneself" , "it comes in handy for washing" .)