Lift head up, getting first prize (7)
I believe the answer is:
Here is my best explanation:
'first prize' is the definition.
'lift head up' is the wordplay.
'lift' becomes 'jack' (jacking is a kind of lifting).
'head up' becomes 'pot' (I can't justify this - if you can you should give a lot more credence to this answer).
'getting' is the link.
(Other definitions for jackpot that I've seen before include "Big payout", "first prize", "Great thing to hit?", "Cumulative prize", "Hit the . . . . . . . - win the big prize", "pool", "Large cash prize", "Accumulated prize", "The big pay-out - hit it" and "major win".)