The most common and most likely answer to this crossword clue is the 4 plus 3 plus 4 plus 3 letter word PUSH THE BOAT OUT
I've seen this crossword clue in The Guardian
P
U
S
H
T
H
E
B
O
A
T
O
U
T
More clues leading to the result PUSH THE BOAT OUT
- Celebrate getting rid of junk?
- Go to town, or go to sea?
- Be lavish and encourage the snake promoter
- Celebrate extravagantly — after cracking a bottle of champagne?
- What RNLI crew may do to celebrate?
- Spare no expense – but path to house needs repair
- What punter might do to celebrate lavishly?
- Start to party with new hot tub at house?
Buddy explains!

The straight part
We know that "Go to town/go to sea" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case go to town/go to sea = push the boat out.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.