Keeps a ship going round a river (5)
I believe the answer is:
stays
'keeps' is the definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Maybe they are linked in a way I don't understand?
'a ship going round a river' is the wordplay.
'a ship' becomes 'SS' (prefix in ship names eg SS Great Britain).
'going round' indicates putting letters inside (some letters go around others).
'a river' becomes 'tay' (Scottish river).
'ss' going around 'tay' is 'STAYS'.
Can you help me to learn more?
(Other definitions for stays that I've seen before include "Boards, lodges" , "for a slimmer figure" , "Remains (in place)" , "Puts up with" , "Supports" .)