Fewer at sea follow coast (9)
I believe the answer is:
freewheel
'coast' is the definition.
(I know that freewheel is a kind of coast)
'fewer at sea follow' is the wordplay.
'at sea' indicates anagramming the letters.
'follow' becomes 'heel' (heeling is a kind of following).
'fewer' anagrammed gives 'freew'.
'freew'+'heel'='FREEWHEEL'
(Other definitions for freewheel that I've seen before include "Move (by bicycle) without pedalling" , "Roll along in neutral gear, be unrestrained" , "The cyclist may" , "powerless to move" , "Coast (on a bicycle) without pedalling" .)