Device that decreases pure stress, or otherwise (7-5)
I believe the answer is:
trouser-press
'device that decreases' is the definition.
I know nothing about this answer so I cannot judge whether it can be defined by this definition.
'pure stress or otherwise' is the wordplay.
'otherwise' is an anagram indicator.
'pure'+'stress'+'or'='purestressor'
'purestressor' is an anagram of 'TROUSER PRESS'.
Can you help me to learn more?
(Other definitions for trouser-press that I've seen before include "Machine found in hotel rooms" , "Flattener for the bottom half of a suit" , "It decreases gents' clothing" , "Means of keeping crease in garment" , "Electrical appliance found in many hotel rooms" .)