And included a trick with a water boa (8)
I believe the answer is:
anaconda
'water boa' is the definition.
(I've seen this before)
'and included a trick with a' is the wordplay.
'included' means one lot of letters goes inside another.
'trick' becomes 'con' (I've seen this before).
'with' means one lot of letters go next to another.
'a'+'con'='acon'
'and' enclosing 'acon' is 'anacond'.
'anacond'+'a'='ANACONDA'
(Other definitions for anaconda that I've seen before include "Strangler" , "1 of 21 [SNAKES]" , "It can constrict" , "Boa constrictor" , "cold-blooded killer" .)