Super-happy thong covers up Serpent (6)
I believe the answer is:
python
'serpent' is the definition.
(I know that python is a type of boa)
'super-happy thong covers up' is the wordplay.
'covers up' indicates the answer is hidden within the clue.
'PYTHON' is hidden in the letters of 'super happy thong'.
(Other definitions for python that I've seen before include "Large non-venomous snake" , "Heavy non-venomous snake" , "Big snake that crushes its prey" , "Boa relative" , "Snake that kills its prey by squeezing" .)