Venomous lizard constructed in smart Lego (4,7)
I believe the answer is:
gila monster
'venomous lizard' is the definition.
(Gila monster is an example)
'constructed in smart lego' is the wordplay.
'constructed' indicates anagramming the letters.
'in'+'smart'+'lego'='insmartlego'
'insmartlego' with letters rearranged gives 'GILA MONSTER'.
(Other definitions for gila monster that I've seen before include "Large venomous lizard" , "US resident" , "venomous attacker" .)