Gas that puts weight on a person (5)
I believe the answer is:
ozone
'gas that' is the definition.
'ozone' can be an answer for 'gas' (thesaurus). I am unsure of the rest of the definition.
'weight on a person' is the wordplay.
'weight' becomes 'oz'.
'on' says to put letters next to each other.
'a person' becomes 'one'.
'oz'+'one'='OZONE'
'puts' acts as a link.
Can you help me to learn more?
(Other definitions for ozone that I've seen before include "bracing atmosphere" , "invigorating British air" , "Ring" , "Condensed oxygen; sea air" , "Bracing air (colloq.)" .)