Information about last of giant amphibians (5)
I believe the answer is:
newts
'amphibians' is the definition.
(newt is a kind of amphibian)
'information about last of giant' is the wordplay.
'information' becomes 'news' (news is a kind of information).
'about' indicates putting letters inside.
'last of' indicates one should take the final letters.
The final letter of 'giant' is 't'.
'news' enclosing 't' is 'NEWTS'.
(Other definitions for newts that I've seen before include "Kind of water lizards or efts" , "creatures" , "Small amphibians, efts" .)