Immature form of life right in centre of volcanic discharge (5)
I believe the answer is:
larva
'immature form of life' is the definition.
(immature form of an insect)
'right in centre of volcanic discharge' is the wordplay.
'right' becomes 'R' (common abbreviation).
'in centre of' indicates putting letters inside.
'volcanic discharge' becomes 'lava' (lava is released in a volcanic eruption).
'r' going into 'lava' is 'LARVA'.
(Other definitions for larva that I've seen before include "Immature form of caterpillar" , "Manage" , "Immature form of (insect) development" , "Maggot" , "Wriggler" .)