It is what it is (7,8)
There are a few possibilities for this:
italian vermouth
'it is what it is' is the definition.
(the word 'it' is a personal pronoun)
'it is what it is' is the wordplay.
'it is' becomes 'personal' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'what it is' becomes 'pronoun' (I've seen this in another clue).
'personal'+'pronoun'='PERSONAL PRONOUN'
(Other definitions for personal pronoun that I've seen before include "us, perhaps" , "We, say" , "Maybe we" .)
If this is the answer, I'm afraid I cannot explain it.
'it' is the definition.
(I've seen this before)
I don't understand the remainder of the clue.
Can you help me to learn more?
(Other definitions for italian vermouth that I've seen before include "Drink" , "two words for it!" , "It expanded" .)