Pandit reversing gas-filled vessel? (5)
I believe the answer is:
nehru
'pandit' is the definition.
(Jawaharlal Nehru was often called Pandit Nehru)
'reversing gas-filled vessel?' is the wordplay.
'reversing' says the letters should be written in reverse.
'gas' becomes 'He' (chemical symbol for helium).
'filled' indicates putting letters inside.
'vessel?' becomes 'urn' (urn is a type of container).
'he' going into 'urn' is 'urhen'.
'urhen' in reverse letter order is 'NEHRU'.
(Other definitions for nehru that I've seen before include "Student of Gandhi" , "India's first prime minister" , "Indian PM 1947-64" , "First prime minister of 5" , "Indian prime minister, father of Indira Gandhi" .)