Go in and Tina will go all out to amuse (9)
I believe the answer is:
entertain
'to amuse' is the definition.
(I've seen this before)
'go in and tina will' is the wordplay.
'go in' becomes 'enter' (as in entering a building).
'and' means one lot of letters go next to another.
'tina will' becomes 'tain' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'enter'+'tain'='ENTERTAIN'
'go all out' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for entertain that I've seen before include "Amuse; host" , "consider" , "harbour" , "Provide amusement" , "Please < flirt with" .)