Gigantic creature, one of `iThem^i? (3)
I believe the answer is:
ant
'gigantic creature' is the definition.
'ant' can be an answer for 'creature' (ant is a kind of animal). I'm not certain of the 'gigantic' bit.
'one of 'ithemi?' is the wordplay.
I cannot really understand how this works, but
'one' could be 'an' (an apple is one apple) and 'an' is found in the answer.
A single letter 't' remains which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for ant that I've seen before include "Dec's long-time partner" , "Social worker" , "The insect lives in a social colony" , "Hill-dweller" , "Six-footer" .)