Cocktail of charm injected with X-Factor (6)
I believe the answer is:
mojito
'cocktail' is the definition.
(rum-based cocktail)
'charm injected with x-factor' is the wordplay.
'charm' becomes 'mojo' (I've seen this before).
'injected with' is an insertion indicator.
'x factor' becomes 'it' (I can't justify this - if you can you should give a lot more credence to this answer).
'mojo' going around 'it' is 'MOJITO'.
'of' is the link.
Can you help me to learn more?
(Other definitions for mojito that I've seen before include "Cuban cocktail with rum as a base" , "Minty cocktail" , "'Cuban cocktail made from rum, lime etc (6)'" , "Mexican cocktail made with white rum and lime juice" , "Cuban rum-and-lime-based cocktail" .)