The most common and most likely answer to this crossword clue is the 4 letter word TOSS
I've seen this crossword clue in The Times
T
O
S
S
More clues leading to the result TOSS
- Lob some balls, so thrown back
- Two sailors on vacation have a restless night, perhaps
- Throw drunkard over top of seawall
- Alcoholic returning to drink? It’s a risk
- To upset cat is a gamble
- Even risks reversing American vessel into position
- Drunk knocked back small drink
- Cast getting drunk over at premiere of Shrek
- Opening action at cricket?
- Fling books round ship
Buddy explains!

The straight part
We know that "have a restless night, perhaps" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case have a restless night, perhaps = toss.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.
What does TOSS mean?
TOSS noun- A throw, a lob, of a ball etc., with an initial upward direction, particularly with a lack of care.
- The coin toss before a cricket match in order to decide who bats first, or before a football match in order to decide the direction of play.
- A haughty throwing up of the head.
- (British slang) A jot, in the phrase 'give a toss'.
- (British slang) A state of agitation; commotion.
- A measure of sprats.
- To throw with an initial upward direction.
- To lift with a sudden or violent motion.
- To agitate; to make restless.
- To subject to trials; to harass.
- To flip a coin, to decide a point of contention.
- To discard: to toss out
- To stir or mix (a salad).
- (British slang) To masturbate
- To search (a room or a cell), sometimes leaving visible disorder, as for valuables or evidence of a crime.
- To roll and tumble; to be in violent commotion.
- To be tossed, as a fleet on the ocean, or as a ship in heavy seas.
- To keep in play; to tumble over.
- To peak (the oars), to lift them from the rowlocks and hold them perpendicularly, the handle resting on the bottom of the boat.
- (British slang) To drink in large draughts; to gulp.