The French and Great Britain with single piece of skeleton (3,4)

'piece of skeleton' is the definition.
'leg bone' can be an answer for 'piece' (leg bone is a kind of piece). I'm not certain of the 'of skeleton' bit.

'the french and great britain with single' is the wordplay.
'the french' becomes 'le' ('the' in French).
'and' says to put letters next to each other.
'great britain' becomes 'gb'.
'with' is a charade indicator (letters next to each other).
'single' becomes 'one' (a single thing - only one).
'le'+'gb'+'one'='LEG BONE'

Can you help me to learn more?