Chuckwalla's cousin (6)
I believe the answer is:
iguana
'chuckwalla's cousin' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for iguana that I've seen before include "Large lizard of tropical Amercia" , "reptile" , "Lizard Darwin found in the Galapagos" , "Large tree-climbing specimen of 5 down in tropical America" , "Arboreal lizard with a spiny crest" .)