In all honesty, many Motherwell fans will be surprised at the continual inclusion of Clarkson in the full squad. He may have been played out of position a lot recently but it is hard to deny his form has dropped considerably since last season. He may have grabbed a respectable if not brilliant tally of four goals so far this term but the last of those came against Rangers on September 21.
Realistically, it is the chronic lack of striking options which have kept Clarkson in contention. He wasn't even on the bench for the Norway game and failed to get onto the park against Northern Ireland, Macedonia or Iceland which suggests Burley is taking him since there is absolutely no one else, especially given the Kris Boyd situation. The other strikers are Iwelumo, Fletcher, Miller and McFadden although McCormack is also named despite his current injury. 
Jamie Murphy's inclusion in the U21 squad is based on merit as he has shown plenty of potential since breaking into the first team this season. He has only found the net a couple of times but his skills at beating players and he can expect to feature in an inexperienced side which has only 32 caps and 4 goals between them.
The experience of being involved can only help both players and we wish them well in representing the country.