You can't say there's no future in it (5)
I believe the answer is:
store
'you can't say' is the definition.
I can't tell whether this definition defines the answer.
'no future in it' is the wordplay.
'no' becomes 'O' (resembles 0 - 'no' can mean 'zero').
'future' becomes 'str' (I am not sure about this - if you are sure you should believe this answer much more).
'in' means one lot of letters goes inside another.
'it' becomes 'e' ('e' can mean 'electronic' which is similar to 'IT').
'o' put inside 'str' is 'stor'.
'stor'+'e'='STORE'
'there's' acts as a link.
Can you help me to learn more?
(Other definitions for store that I've seen before include "Eg, granite" , "Supply available for future use" , "Shop; repository" , "Reserve, shop" , "Stock or supply, or warehouse for them" .)