At first, snipping cascading black hair presents obstacles (9,6)

'obstacles' is the definition.
(a stumbling block is a difficulty or obstacle)

'at first snipping cascading black hair' is the wordplay.
'at' is a charade indicator (letters next to each other).
'first snipping' becomes 's' (1st letter of 'snipping').
'cascading' becomes 'tumbling' (to cascade is to fall or tumble).
'black' becomes 'b' (as in pencil classifications).
'hair' becomes 'locks' (locks can mean hair).
's' next to 'tumbling' is 'stumbling'.
'stumbling'+'b'+'locks'='STUMBLING-BLOCKS'

'presents' acts as a link.