Traveller in pain on small yacht's prow (5)
I believe the answer is:
gypsy
'traveller' is the definition.
(gypsy is a kind of traveller)
'pain on small yacht's prow' is the wordplay.
'pain' becomes 'gyp' (I've seen this before**).
'on' means one lot of letters go next to another.
'prow' says to take the initial letters.
The initial letters of 'small yachts' is 'sy'.
'gyp'+'sy'='GYPSY'
'in' acts as a link.
(Other definitions for gypsy that I've seen before include "old Broadway play" , "Romany" , "Member of a normadic people" , "Traveller" .)