Going back, again immerses the creature (6)
I believe the answer is:
spider
'the creature' is the definition.
(spider is a kind of creature)
'going back again immerses' is the wordplay.
'going back' says the letters should be written backwards.
'again immerses' becomes 'redips' ('dips' is an answer for 'immerses' so perhaps 'redips' is OK for 'again immerses').
'redips' in reverse letter order is 'SPIDER'.
(Other definitions for spider that I've seen before include "Webster" , "Spinner" , "A crawler" , "Prised out the insect" , "website designer?" .)