One maybe operating still from cell in Merseyside town by river (10)
I believe the answer is:
bootlegger
'one maybe operating still' is the definition.
(a still is used to prepare alcoholic spirits)
'cell in merseyside town by river' is the wordplay.
'cell' becomes 'egg' (egg is a kind of cell).
'in' is an insertion indicator.
'merseyside town' becomes 'Bootle' (town in Merseyside, North West England).
'by' is a charade indicator (letters next to each other).
'river' becomes 'r' (abbreviation for river).
'egg' going into 'bootle' is 'bootlegge'.
'bootlegge'+'r'='BOOTLEGGER'
'from' is the link.
(Other definitions for bootlegger that I've seen before include "Distributor of illegal alcohol" , "Criminal" , "Purveyor of illegal alcohol or recordings" , "One operating still" , "pirate" .)