Oh, sports lingo. That phrase is used in the sports that involve goals, and in your text is, simply, an elided version of send someone clear on goal, someone, of course, being the fellow player. The adjective clear refers to the fellow player not being surrounded by any opposing defenders (not counting the goalie). The verb send refers to prompting the teammate to move to the location where the ball will fall after being hit.
Edit (the day after):
Regarding both my answer and the definition of clear in Mykola's answer, I've been sent an email with a definition of clear from a paper dictionary, Dictionary of Sports and Games Terminology by Adrian Room, published in 2010. It reinfirces the conclusion that there's a difference between send someone clear—and just clear (or clearance, as recorded in that dictionary).
###clearance
(association football)
a defensive kick away from a dangerous attacking position
(field hockey)
a defensive hit away from a dangerous attacking position###hit
(general)
a stroke or shot that sends a ball or other missile (as an arrow in archery or a round in shooting) to a target or simply through the air
But I started to wonder about the kicked ball in the situation of sending someone clear; I suspected that it might necessarily mean that the ball was kicked defensively, to prevent the opposing team's attack, and not during the offense. It was a false alarm. A well-specified internet search proved my original answer correct. Here are some situations in which it is obvious that sending clear can happen during the offense:
- Their best chance came off a line break by Ross Rennie in the second half but he delayed with Mike Blair and Laidlaw screaming to be sent clear to his left
- Elding was doing good work for Town, chasing down defenders and chesting the ball down to enable Hearn to be sent clear, but off side was given.
- GOOOALLL! Incredible, Chelsea go up the other end of the pitch and Malouda makes it 4-1! Malouda is sent clear on goal. He shoots and Fabianski parries, but only to Anelka who shoots but hits the post! However, the ball rebounds kindly back to an offside Malouda to slot home.
(I'm gonna git me that dictionary and the next time I channel-surf I'm gonna stop on that ESPN, even if damned I be.)
I also wondered whether clear was, perhaps, a nominal adjective referring to the ball (to be sent a clear), so I included the indefinite article in the Google search... Zero results. So, that's that.