Riverside resident has home set up with group (5)

'riverside resident' is the definition.
(someone from the region around the River Nile)

'home set up with group' is the wordplay.
'home' becomes 'in' ('he's home' can mean 'he's in').
'set up' is a reversal indicator (in a down clue, letters go up).
'with' means one lot of letters go next to another.
'group' becomes 'lot'.
'in' in reverse letter order is 'ni'.
'ni'+'lot'='NILOT'

'has' is the link.