That little extra that makes the star higher (3-2)
I believe the answer is:
top-up
'that little extra that' is the definition.
I can't tell whether this defines the answer.
'the star higher' is the wordplay.
I cannot really see how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
'higher' could be 'up' and 'up' is present in the answer.
The remaining letters 'op' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'makes' acts as a link.
Can you help me to learn more?
(Other definitions for top-up that I've seen before include "Supplement" , "Amount required to restore something's level" , "Additional amount to restore mobile phone credit, for example" , "Extra addition" , "Replenished drink" .)