Got so involved in select toy (4,5)
I believe the answer is:
pogo stick
'toy' is the definition.
(I know that pogo stick is a type of toy)
'got so involved in select' is the wordplay.
'involved' indicates an anagram (involved can mean confusing or complex).
'in' indicates putting letters inside.
'select' becomes 'pick' (picking is a kind of selecting).
'got'+'so'='gotso'
'gotso' with letters rearranged gives 'ogost'.
'ogost' going within 'pick' is 'POGO STICK'.
(Other definitions for pogo stick that I've seen before include "Jumping rod with a spring" , "Jumping toy" , "On which kids bounce along" .)